BU-409: Charging Lithium-ion. 18650 lithium battery charger

BU-409: Charging Lithium-ion

Charging and discharging batteries is a chemical reaction, but Li-ion is claimed to be the exception. Battery scientists talk about energies flowing in and out of the battery as part of ion movement between anode and cathode. This claim carries merits but if the scientists were totally right, then the battery would live forever. They blame capacity fade on ions getting trapped, but as with all battery systems, internal corrosion and other degenerative effects also known as parasitic reactions on the electrolyte and electrodes still play a role. (See BU-808b: What causes Li-ion to die?)

The Li-ion charger is a voltage-limiting device that has similarities to the lead acid system. The differences with Li-ion lie in a higher voltage per cell, tighter voltage tolerances and the absence of trickle or float charge at full charge. While lead acid offers some flexibility in terms of voltage cut off, manufacturers of Li-ion cells are very strict on the correct setting because Li-ion cannot accept overcharge. The so-called miracle charger that promises to prolong battery life and gain extra capacity with pulses and other gimmicks does not exist. Li-ion is a “clean” system and only takes what it can absorb.

Charging Cobalt-blended Li-ion

Li-ion with the traditional cathode materials of cobalt, nickel, manganese and aluminum typically charge to 4.20V/cell. The tolerance is /–50mV/cell. Some nickel-based varieties charge to 4.10V/cell; high capacity Li-ion may go to 4.30V/cell and higher. Boosting the voltage increases capacity, but going beyond specification stresses the battery and compromises safety. Protection circuits built into the pack do not allow exceeding the set voltage.

Figure 1 shows the voltage and current signature as lithium-ion passes through the stages for constant current and topping charge. Full charge is reached when the current decreases to between 3 and 5 percent of the Ah rating.

Li-ion is fully charged when the current drops to a set level. In lieu of trickle charge, some chargers apply a topping charge when the voltage drops.

The advised charge rate of an Energy Cell is between 0.5C and 1C; the complete charge time is about 2–3 hours. Manufacturers of these cells recommend charging at 0.8C or less to prolong battery life; however, most Power Cells can take a higher charge C-rate with little stress. Charge efficiency is about 99 percent and the cell remains cool during charge.

Some Li-ion packs may experience a temperature rise of about 5ºC (9ºF) when reaching full charge. This could be due to the protection circuit and/or elevated internal resistance. Discontinue using the battery or charger if the temperature rises more than 10ºC (18ºF) under moderate charging speeds.

Full charge occurs when the battery reaches the voltage threshold and the current drops to 3 percent of the rated current. A battery is also considered fully charged if the current levels off and cannot go down further. Elevated self-discharge might be the cause of this condition.

Increasing the charge current does not hasten the full-charge state by much. Although the battery reaches the voltage peak quicker, the saturation charge will take longer accordingly. With higher current, Stage 1 is shorter but the saturation during Stage 2 will take longer. A high current charge will, however, quickly fill the battery to about 70 percent.

Li-ion does not need to be fully charged as is the case with lead acid, nor is it desirable to do so. In fact, it is better not to fully charge because a high voltage stresses the battery. Choosing a lower voltage threshold or eliminating the saturation charge altogether, prolongs battery life but this reduces the runtime. Chargers for consumer products go for maximum capacity and cannot be adjusted; extended service life is perceived less important.

Some lower-cost consumer chargers may use the simplified “charge-and-run” method that charges a lithium-ion battery in one hour or less without going to the Stage 2 saturation charge. “Ready” appears when the battery reaches the voltage threshold at Stage 1. State-of-charge (SoC) at this point is about 85 percent, a level that may be sufficient for many users.

Certain industrial chargers set the charge voltage threshold lower on purpose to prolong battery life. Table 2 illustrates the estimated capacities when charged to different voltage thresholds with and without saturation charge. (See also BU-808: How to Prolong Lithium-based Batteries)

Adding full saturation at the set voltage boosts the capacity by about 10 percent but adds stress due to high voltage.

When the battery is first put on charge, the voltage shoots up quickly. This behavior can be compared to lifting a weight with a rubber Band, causing a lag. The capacity will eventually catch up when the battery is almost fully charged (Figure 3). This charge characteristic is typical of all batteries. The higher the charge current is, the larger the rubber-Band effect will be. Cold temperatures or charging a cell with high internal resistance amplifies the effect.

The capacity trails the charge voltage like lifting a heavy weight with a rubber Band.

Estimating SoC by reading the voltage of a charging battery is impractical; measuring the open circuit voltage (OCV) after the battery has rested for a few hours is a better indicator. As with all batteries, temperature affects the OCV, so does the active material of Li-ion. SoC of smartphones, laptops and other devices is estimated by coulomb counting. (See BU-903: How to Measure State-of-charge)

Li-ion cannot absorb overcharge. When fully charged, the charge current must be cut off. A continuous trickle charge would cause plating of metallic lithium and compromise safety. To minimize stress, keep the lithium-ion battery at the peak cut-off as short as possible.

Once the charge is terminated, the battery voltage begins to drop. This eases the voltage stress. Over time, the open circuit voltage will settle to between 3.70V and 3.90V/cell. Note that a Li-ion battery that has received a fully saturated charge will keep the voltage elevated for a longer than one that has not received a saturation charge.

When lithium-ion batteries must be left in the charger for operational readiness, some chargers apply a brief topping charge to compensate for the small self-discharge the battery and its protective circuit consume. The charger may kick in when the open circuit voltage drops to 4.05V/cell and turn off again at 4.20V/cell. Chargers made for operational readiness, or standby mode, often let the battery voltage drop to 4.00V/cell and recharge to only 4.05V/cell instead of the full 4.20V/cell. This reduces voltage-related stress and prolongs battery life.

Some portable devices sit in a charge cradle in the ON position. The current drawn through the device is called the parasitic load and can distort the charge cycle. Battery manufacturers advise against parasitic loads while charging because they induce mini-cycles. This cannot always be avoided and a laptop connected to the AC main is such a case. The battery might be charged to 4.20V/cell and then discharged by the device. The stress level on the battery is high because the cycles occur at the high-voltage threshold, often also at elevated temperature.

A portable device should be turned off during charge. This allows the battery to reach the set voltage threshold and current saturation point unhindered. A parasitic load confuses the charger by depressing the battery voltage and preventing the current in the saturation stage to drop low enough by drawing a leakage current. A battery may be fully charged, but the prevailing conditions will prompt a continued charge, causing stress.

Charging Non-cobalt-blended Li-ion

While the traditional lithium-ion has a nominal cell voltage of 3.60V, Li-phosphate (LiFePO) makes an exception with a nominal cell voltage of 3.20V and charging to 3.65V. Relatively new is the Li-titanate (LTO) with a nominal cell voltage of 2.40V and charging to 2.85V. (See BU-205: Types of Lithium-ion)

Chargers for these non cobalt-blended Li-ions are not compatible with regular 3.60-volt Li-ion. Provision must be made to identify the systems and provide the correct voltage charging. A 3.60-volt lithium battery in a charger designed for Li-phosphate would not receive sufficient charge; a Li-phosphate in a regular charger would cause overcharge.

Overcharging Lithium-ion

Lithium-ion operates safely within the designated operating voltages; however, the battery becomes unstable if inadvertently charged to a higher than specified voltage. Prolonged charging above 4.30V on a Li-ion designed for 4.20V/cell will plate metallic lithium on the anode. The cathode material becomes an oxidizing agent, loses stability and produces carbon dioxide (CO2). The cell pressure rises and if the charge is allowed to continue, the current interrupt device (CID) responsible for cell safety disconnects at 1,000–1,380kPa (145–200psi). Should the pressure rise further, the safety membrane on some Li-ion bursts open at about 3,450kPa (500psi) and the cell might eventually vent with flame. (See BU-304b: Making Lithium-ion Safe)

bu-409, charging, lithium-ion, 18650, lithium

Venting with flame is connected with elevated temperature. A fully charged battery has a lower thermal runaway temperature and will vent sooner than one that is partially charged. All lithium-based batteries are safer at a lower charge, and this is why authorities will mandate air shipment of Li-ion at 30 percent state-of-charge rather than at full charge. (See BU-704a: Shipping Lithium-based Batteries by Air)

The threshold for Li-cobalt at full charge is 130–150ºC (266–302ºF); nickel-manganese-cobalt (NMC) is 170–180ºC (338–356ºF) and Li-manganese is about 250ºC (482ºF). Li-phosphate enjoys similar and better temperature stabilities than manganese. (See also BU-304a: Safety Concerns with Li-ion and BU-304b: Making Lithium-ion Safe)

Lithium-ion is not the only battery that poses a safety hazard if overcharged. Lead- and nickel-based batteries are also known to melt down and cause fire if improperly handled. Properly designed charging equipment is paramount for all battery systems and temperature sensing is a reliable watchman.


Charging lithium-ion batteries is simpler than nickel-based systems. The charge circuit is straight forward; voltage and current limitations are easier to accommodate than analyzing complex voltage signatures, which change as the battery ages. The charge process can be intermittent, and Li-ion does not need saturation as is the case with lead acid. This offers a major advantage for renewable energy storage such as a solar panel and wind turbine, which cannot always fully charge the battery. The absence of trickle charge further simplifies the charger. Equalizing charger, as is required with lead acid, is not necessary with Li-ion.

Consumer and most industrial Li-ion chargers charge the battery fully. They do not offer adjustable end-of-charge voltages that would prolong the service life of Li-ion by lowering the end charge voltage and accepting a shorter runtime. Device manufacturers fear that such an option would complicate the charger. Exceptions are electric vehicles and satellites that avoid full charge to achieve long service life.

Simple Guidelines for Charging Lithium-based Batteries

  • Turn off the device or disconnect the load on charge to allow the current to drop unhindered during saturation. A parasitic load confuses the charger.
  • Charge at a moderate temperature. Do not charge at freezing temperature. (See BU-410: Charging at High and Low Temperatures)
  • Lithium-ion does not need to be fully charged; a partial charge is better.
  • Not all chargers apply a full topping charge and the battery may not be fully charged when the “ready” signal appears; a 100 percent charge on a fuel gauge may be a lie.
  • Discontinue using charger and/or battery if the battery gets excessively warm.
  • Apply some charge to an empty battery before storing (40–50 percent SoC is ideal). (See BU-702: How to Store Batteries.)


[1] Courtesy of Cadex

The material on Battery University is based on the indispensable new 4th edition of Batteries in a Portable World. A Handbook on Rechargeable Batteries for Non-Engineers which is available for order through Amazon.com.

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charger socket on my Google Mobile has expanded and not retaining charger plug which keeps dropping off, can I replace Mobile socket ?

I need a tutor help for lifepo4 Plz share contact no

I am working on a way to recharge the batteries in a transponder I know the base voltage the trouble is that I will need to charge at 0.99 volts to actively charge the battery but not activate the transponder now as we know most chargers charge at at least 1.1 volts using my calculation I will need 1 15000 mic capacitor and 3 resistors the value on ly I know what do I have to look for in fall rate and could I require the transponders permission to do this type of thing

This is a very good website which concerns on how to maintain any kind of battery.

What a wonderful, informative write up! Great site folks. Thanks.

This excellent article describes that dangerous overcharging is likely if we charge a 3.7V lithium ion cell at 4.2V and forget. in the constant voltage phase. to switch off charging after the current has dropped to one tenth of the initial value. But will this overcharging be a risk at all charging voltages all the way down to the minimum voltage that can move ions within the battery (around 3.4V, I guess). Put differently, is there a voltage between the minimum (3.4V?) and 4.2V at which it is safe to simply let the constant voltage phase run forever?

If such a lower safe voltage does not exist, how long would it take before charging at, say, 3.9V would start to cause trouble? Hours, days, weeks?

I’m asking because I have a setup that can store energy from solar panels in a lithium ion battery and where it would be ideal to just cap the charging voltage of each cell at 3.9V in place of introducing a real charger.

There is a lithium battery in my wifes battery box. It is 12 v for her mobility scooter. Apart from the word, lithium it gives no further details. She has a charger but that is for her secong battery that is a lead acid one. I believe its not suitable a charger for lithium’s. Is there a way to tell which lithium type? Also what would be a typican current flow when charging the lithium battery and would the voltage by ok at 4 volts? Thank you.

First thanks for the very useful information which is based on practical tests, very trusty and thus helpful for me. One use case that often occours for my lithium devices are short charge disruptions (miliseconds to secons). What are the shortlong term impacts for lithium batteries considering the lifetime of the battery? (some evidence-based explanation similarly like figure 6 in bu-808-how-to-prolong-lithium-based-batteries would be very helpful). Thanks

Lead acid batteries cannot take a high voltage when charging like LiPoFe can when charging. Your motorcycle alternator charging system made for lead acid batteries and cannot overcharge your new LiPo battery unless the bike was left running for 24-48 hours strait. Even then there is a float charge where the battery will stop charging at the highest point, this is installed on the alternator and is set for a 12v battery and cannot be changed, or in some cases the battery itself will have a float limit installed. In short, a LiPoFe battery can take more charge faster than a lead acid battery can, so any charging system that will charge lead acid, will be like a trickle charger for the LiPoFe battery and will not harm the LiPoFe battery at all. As long as the lithium battery and lead acid charger are both rated for 12V.

A lithium battery charger will damage a lead acid battery by overcharging it with high voltage. But not the other way around.

What about short charge disruptions (1-10seconds), do they damage the battery lifetime? According to Figure6 in your article https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries short SoC bandwiths are also not benefical as the battery delivers less power units in the end, but i dont know if short disruption count as cycles.

Lithium iron phosphate formulation need please guide

I purchased one camera F65 from gowda movies with which I received two packs of batteries lithium ion and a charger from power india input is

Given the complexity of battery charging across lead acid/ NIMH/ NIcad/ Li, how can they sell me an Li 12v battery for my motorcycle which originally came in 2004 with lead acid battery? Where’s the regulation of current? It has to be in the battery, right?

Hello, is it true that a cell cannot charge to a higher voltage than the voltage available at the output of the charger? If the charger presents 4.2 V, how can the cell charge to a voltage higher than 4.2 V? Thx

dear sir i have bought a oukitel wp15 phone and i am asking what is the best way to charge the battery lithium-ion polymer in order to let the battery lives long and prevent the damage for it should i charge it from 65% to 75% is that the best way ithank you in advance

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Any info on how this applies to the various adaptive charging protocols in Li-ion devices like smartphones (I.e. Qualcomm’s Quick Charge)? I know the power supply can deliver a higher voltage to the phone, but how is that then fed to the battery? Let’s say you have 9V/2A going to the phone from the power supply. Is the battery then being fed a 9V input voltage, or is the phone’s charging circuit stepping it down to a typical input voltage with a boost in amperage?

I have overcharged a Samsung INR18650-25R (18650 Li-Ion LiNiMnCoO2 2500 mAh / 10C) to 4.28V. I had 2 of these cells charging in serie and a bad contact has caused one to reach 4.28V. When the bad contact was suddenly resolved the charger has detected the 4.28V voltage on one cell through the balance port and has stopped the charge (I was nearby so I have heard the charger alarm immediately). My DMM has then confirmed the 4.28V voltage on one cell, and this cell wasn’t hot by touching with the hand. After 45min (reading here to find some infos and preparing a discharge procedure) this cell voltage was down below 4.22V, and the cell is now discharging at 200mA to reach 4.11V (to match the other cell, as I use both combined in an electronic cigarette). Should I now consider this cell unsafe and replace it ? (especially since I use it in a device I hold in my hand and near my mouth/head/eye).

It is suggested that Lithium-Ion batteries be stored at a 50% state of charge. How do I know what this is? I have a voltmeter and can measure voltage but then what? I have a 80v lawnmower. Is 50% charge 75v, 70v. 60v? Any suggestions appreciated.

Hi, How can I calculate the charge time of the last 16% of the total capacity of a typical lithium battery to give a SOC = 100%? My charger is Bosch’s 6 A and the output voltage is 36 V, or 216 W. Thanks Best regards

Is it possible to create a ‘battery’ connector with a cigarette lighter plug or car battery clamps to power a battery powered impact wrench? Perhaps that would be an idea for a product. It would be great to be able to use your model as an emergency tool for autos and trucks without the problems associated with storing a battery in those conditions.

If I want to charge my L-ion cells to 80%, would it be better (from the point of view of cell longevity) to charge to 4.1V per cell without saturation, or would it be better to charge to 4.0V per cell with full saturation?

Hi Battery University, I’m finishing up building a Robotic car with Arduino smarts. Have dg01d mini gear box servo motors powered by 4.5vdc. I would like to know: 1) The options for the type of batteries to use to power 3-4 servo motors. 2) The number of batteries needed to power 3. servos. And options for 3) Charging. The charging power source will be 120vac but not sure if solar can be used. Fast charging time might be useful. Joe M

@ TERENCE MORRIS, It sounds like you either have defective batteries, or you purchased a 3rd party battery. I’m assuming, being the Smart man you are, that you DIDNT: Store the batteries for extended periods of time, Frequently keep batteries in a low/high state of charge (20%/80%) Allow excessive temperatures (90F/100F) or Allow them to drop to zero, or even below 20%. That the Batteries are relatively new (only a handful of charges) The problem with 3rd party, is that they used inferior chemicals/parts/ production quality. Or, it could have been a used battery, which was relabeled. If you purchased a genuine OEM battery, but did not do so through a reputable seller (Think ebay/Amazon 3rd party sellers), Then, there’s a good chance (almost guaranteed) you received a 3rd party inferior battery. A non-scientific way to test this, is to weigh your original OEM battery in grams, and compare it the weight of the ones you’re currently using. 3rd Party are commonly significantly lighter than OEM There’s a reason why 4 eBay Genuine OEM smartphone batteries are so cheap, compared to actual OEM. They’re also MUCH lighter than OEM. These also have a tendency for the phones to shut off at 40-50%, and have to use 3 to get through the day VS 1 OEM only using up 40-60% capacity, during the day. If you have any electrical skills, you can test the batteries with a multimeter, using tests frequently found on google. You need to purchase new batteries. Make sure they’re OEM, AND sold by a reputable seller (ie. Amazon warehouse, not AMZN 3rd party sellers) Cheers, Jimmy

Hello, thanks for all this webpage information, it is really amazing Im in a project that will use a 3,7 Lipo battery with around 100mA. My device will consume just few microamps in a range of 5 to 10. My need is to extend the device battery life as much as possible and i will use a small solar cell. This solar cell will be also in a placement with not so many light that it will just give me around 2uA. My question and big dubt is if, with such small solar cell output current i will be even able to start to charge the battery. Hope someone can help me thanks in advanced!

I would like to know, how do I develop a security charger that cuts off power at the time the phone is in use.

ANTIQUE ELECTRIC CAR I own a 1919 Milburn Electric car and would like to purchase lithium LIFePO4 batteries instead of the using the original lead acid batteries. The motor is a 76 volt 33amp DC GE motor from the era. The original system voltage was 84 volts (42 cells in 2 modules or 21 cells each) The manual controller with 12 brass contact fingers is organized as follows : “gear” 1 slowest speed, wheels beginning to turn, most ‘torque’ the motor is energized at 42 volts with the 2 modules in parallel and a resistor in place “Gear” 2 slightly faster and ‘torque’ still required to gain speed The motor is energized at 42 volts with the 2 modules in parallel and less resistance “Gear” 3 medium speed The motor is energized at 84 voltswith the 2 modules in series and even less resistance “Gear” 4 high speed least amount of ‘torque’ The motor is energized at 84 volts with the 2 modules in series and no resistors In “off” mode the lead acid cells were placed in series and the charger provided 84 volts. I have been talking to a lithium cell supplier who is willing to supply sufficient LIFePO4 120amp cells in 2 seperate and equal modules to provide nominally 42 volts each and a BMS for each These modules are recommended to be wired in series only for 84 volts and that they stay that way He does not recommend that they be connected alternately in parallel for 42 volts 240 amps. I am assuming that there is a concern that the 2 lithium ion modules will become out of balance with each other and risk fire and explosion A consistent 84 volt system will not work in this car Any suggestions that would lead to successful usage of lithium cells in 2 equal but separate 42 volt modules? Thank you

I have two new 2600mAh camera batteries that I’m unable to charge properly after only a handful of charge cycles. The weird thing is when they are fully discharged the charger reports them as 90% charged. After charging to100% I only get around 5 minutes use from them whereas new they gave me around an hour (I use them to power a 7 camera monitor). I checked with a voltage meter and they definitely have zero voltage output when discharged. I doubt the charger is faulty as I have two identical chargers and both give 90% percentage readouts when the batteries are definitely flat. What is going on?

Hello, I have a LiFePo4 battery for an EV. I want to extend its life as much as possible. What would be the optimal charging time? (made of 2,5 Ah 3,3 V cells). Need to use 80% DOD. Thank You!

Should I use PWM Solar Charge controller to charge Li-ion Battery. I think that Spike of PWM can cause fire or burn Li-ion Battery. Please confirm.

can this lithium battery be recharged? label on battery says GEBC Lithium Battery, BATT-D103-4, REF:A340301 10.8V 19Ah, ASM by GE Battery, China 33/15

Q: David Maxfield wrote: My Bosch EBike charger has failed and the replacement is quite expensive.Is it ok to just source an alternative cheaper brand of charger as long as the output voltage and current are the same ? A: That should be ok because the electronics in the battery pack will balance the pack and cut off the charge current when the battery is full Be aware that the original charger may have more than 2 connections ( and.) that may have an effect on the charging process To be 100% safe you should use the recommended charger

My Bosch EBike charger has failed and the replacement is quite expensive.Is it ok to just source an alternative cheaper brand of charger as long as the output voltage and current are the same ?

illumiin wrote: I have a question! I’m using iPhone and i only charge my phone by Laptop via USB host. But when i check my phone by software such as “3utools” or similar…, i realize my phone (battery) has max voltage’s 4.47V when max capacity. I think it’s a Li-ion battery type, and at 4.2V, my battery only has 80% capacity! Is that normal. Answer: When charging with USB and a cable that comes with your phone or is suitable for your phone your phone will charge until it reaches its maximum capacity The electronics inside the phone and battery will prevent overcharging Software may not be accurate when measuring voltages from the battery When connected to computer USB or wall charger your phone will always charge until it’s full no matter what the maximum voltage of your battery is

michael porporo wrote: do batteries need to be completely depleted before charging? Answer: No, li-ion batteries can be charged at any time, they don’t have to be empty

Wildeman Victor wrote: What will happen with my Li Lion 18650 if i charge them only with cv and the current fluctates every secound, like charging on a Solar cell? Lifetime crtitc? Capacity is a little less then cc cv…? Answer: cc or constant current is important because you don’t want to charge cells with a too high current, constant voltage is important because you don’t want to overcharge cells with too high of a voltage so you can have a constant voltage of 4.2 volt with a start current of 30 amps, this will be bad for the cell A proper charger will limit the current to lets say 1 amp and limit the voltage to 4.2 volt The charger will drop the voltage down until the cell receives 1 amp, when the cell amperage drops below 1 amp the voltage goes up but will never go over the set 4.2 max. voltage I Hope this helps

Scott Johnson wrote: I’ve got a pair of 18650s I’ve been carrying as spares. They were fully charged about a year ago so they’ve been stable. I measured their voltage thinking I could learn something about their state of charge. and they both measure 4.085 volts on a NIST-traceable calibrated voltmeter. Most of what I read here says that voltage is impossible and that it should be settled somewhere below 4V. Are they overcharged? Answer: The voltage after charge will drop off or settle lower than the charge voltage, when charged to 4.2 volt the voltage will settle anywhere between 4 and 4.2 volt and over time it can drop lower due to to self discharge At least that’s my experience with healthy li-ion cells (they should hold 4 volt over at least a couple of weeks)

Stephen Tice wrote: I am using old 18650 cells from laptop computers hocked up in series to get 37.80 volts to run a 9 Led flush light. I works well and I have tested it several times. I discharged the battierys to.13%.The problem is I am charging the 9 cells up one at a time and it takes much time ! Is there a charger I can use that will charge at 37.8 plus volts that will do the same job with out damaging the cells? 2nd question, what % can I discharge this battery doun to without damaging the cells? I am using old 18650 cells from laptop computers hocked up in series to get 37.80 volts to run a 9 Led flush light. I works well and I have tested it several times. I discharged the battierys to.13%.The problem is I am charging the 9 cells up one at a time and it takes much time ! Is there a charger I can use that will charge at 37.8 plus volts that will do the same job with out damaging the cells? 2nd question, what % can I discharge this battery doun to without damaging the cells? Answer: You could make two groups of 5 cells in series and 4 cells in series then connect the two groups in series and charge them separate with a (cheap) li-ion charger with balance charge capability The cheapest charger I could find will only do 6s or 6 cells in series max. You would have to do some research online and make groups with a balance connector (not that hard to do) The lowest voltage for discharge is 3 volt per cell before you cause damage some cells can go to 2.5 volt but 3 volt is a safe cut off There are cell voltage alarms available for RC hobby that can help out with a voltage alarm to let you know when the cells get to low

An e-bike battery (home made) with 12 cells in parallel is being charged to 4.10 volt end voltage The cut off amperage is 0.1 amp and during the charging the current will slowly drop off from lets say 6A to 0.1A During the charging the amperage will reach 0.5 Amp for example at which point the amperage per cell will be 0.5A/12 cells = 0.41mA possibly for an hour or longer Will this damage the cells? Is this considered trickle charging over a long period of time? The solution would be a high power charger that can deliver 12 amps or more with a higher cut off amperage but my main concern is, will this damage the cells if the end voltage is set at 4.10 volt or possibly lower at 4.0 volt? The issue here is not how to properly charge one cell but more what happens if you put multiple cells in parallel and the charge current per cell drops significantly which is mostly the case in high power applications such as e-bikes that require high amperage to run properly

I have a CPAP battery pack, a Medistrom, Pilot-12 Plus, cell type is described as Industrial grade genuine rechargeable lithium ion cells manufactured by LG® and I am recharging it with my semi truck’s invertor. Do I need a pure sine power supply?

I am using old 18650 cells from laptop computers hocked up in series to get 37.80 volts to run a 9 Led flush light. I works well and I have tested it several times. I discharged the battierys to.13%.The problem is I am charging the 9 cells up one at a time and it takes much time ! Is there a charger I can use that will charge at 37.8 plus volts that will do the same job with out damaging the cells? 2nd question, what % can I discharge this battery doun to without damaging the cells?

I’ve got a pair of 18650s I’ve been carrying as spares. They were fully charged about a year ago so they’ve been stable. I measured their voltage thinking I could learn something about their state of charge. and they both measure 4.085 volts on a NIST-traceable calibrated voltmeter. Most of what I read here says that voltage is impossible and that it should be settled somewhere below 4V. Are they overcharged?

What will happen with my Li Lion 18650 if i charge them only with cv and the current fluctates every secound, like charging on a Solar cell? Lifetime crtitc? Capacity is a little less then cc cv.

I have a robot mower whose charging circuit has broken. It only deliver 1.5V instead of 24V. Normally the robot homes on 2 big spikes to get recharged. I just got a 6-cell stand-alone charger. I took the battery out and see that it has 6 terminals labelled., T,BH,Vcc,BS, If I connect the charger to and. is is likely to charge, explode, or what? The manufacturer (Worx) doesn’t answer so I am in the dark here. I would be grateful for any info.

I have a question regarding how much the life time will be effected in an UPS battery which needs to maintain a fully charged battery for a long period of time(years). (With fully charged battery I thinking around 80% SoC) 1. Is it recommended to maintain battery voltage for 80% SoC for many years? 2. Is it better to lower SoC to 60-70%, will it prolong the total life time of the battery? 3. Is it important to do cell balancing even thou the SoC of battery is around 60-80% instead of 100%?

I have a question! I’m using iPhone and i only charge my phone by Laptop via USB host. But when i check my phone by software such as 3utools or similar. i realize my phone (battery) has max voltage’s 4.47V when max capacity. I think it’s a Li-ion battery type, and at 4.2V, my battery only has 80% capacity! Is that normal.

Hi, I have an Intergy Kodiak solar generator that uses a 1100 WH Li NMC battery. They claim it has a 2000 cycle service life and they recommend leaving it fully charged, and on the charger at all times. Based on your article, it seems to me I should limit charging to 40. 50 % when I’m not using it and try to get by with a 70% charge to maximize the service life. Is that correct? I wonder why Intergy would recommend leaving it on a charger continuously.

Hello. I would like to know about quick charge (Qualcomm technology). That make battey not stable right ? Let’s explain about how quick charge effect to battery please !

Hi i wondered when you charge a battery with a charger can it ever read more then 4.20 volt on a multi meter ? the charger does use CC CV. but i want to see if there is an y difference when i feed the charger 4.3 volt (4 is minimum) or 6 volt which is still within the specs. i ask, this to decrease heat. i noticed giving the charger less voltage generates less heat and i wonder how low i can go. the charge current remains the same in all cases. i sort of want to force the charge chip a 4057A to manipulate as little as possible (less heat) but since it some how is longer on the charger i wondered if i am not over charging the bat

i would like to know what to write in Reference as citation if i have wrote up a thesis by taking some information from this page, as an example i took figure 1 charge stages of lithium ion for my thesis but i couldnt find any citation for that picture. Need some help on citation for that. have a great day.

I have a question for a NiMh battery expert. I am building a 22 NiMh battery array and need to know how to charge it quickly and safely. It is going to consist of 22 type NUN 3000s in series (1.3Volt, 3000MaH). I need to know how to best charge these.I am assuming I will need to have thermal sensors to prevent overheating. Any help would be much appreciated. Thanks

Does charging your battery to 80% and discharging it to 50% make it last three times longer than it would if I charged it all the way to 100% and discharge it to 10%? Btw I am not a geek and that is why my peanut brain couldn’t understand the above explanation.

I would like to know if a supply voltage of 4.00 volts is hooked up to a lithium ion battery (4.20 volts 100% SOC), can the 4.00 volts be left on indefinitely? And be safe? If not, is there a power supply voltage level that would be safe? I.e 3.95, 3.90, 3.80, etc.? The 4.oo volt supply would allow for trickle charging up to 75% SOC and the battery would available for a short term high current draw as required from the battery.

Hi, I am building a small home solar system to store power. The plan is to be able to use that power on my ebike. Currently I have 2 52V 13.5ahr lithium ion battery packs for my bike that I switch in and out. I have purchased some 100W panels as well as an http charge controller. My question is should I store the solar energy in a higher capacity batter (or a lead acid) and then charge my lithiums from that battery, and how would I do that safely. Or can I charge the Lithiums directly from the sun?

My colleague read somewhere that the best way to charge battery pack is using current for a single cell. So for 18650 is 0.8C of a max today 3500mAh. Even if a battery pack have configuration 2S6P for example. Is it true? I mean it’ll take too long.

Great article. I have been confused for a long time about charging and howbit affects battery life, especially Li-ion batteries, now I have digested this article and I understand how it works. Am glad I found this article.

I am using Li-ion 5800mAh 3.7v batteries for flashlights. Should I discharge them all the way before recharging them?

My Android phone’s battery is removable. I have recently bought a second battery, so now I charge one in an external charger while using the other. The problem is that when swapping the batteries Android Marshmallow always shows the same percentage for the new battery as for the old. Therefore, I can never really know what the true percentage is of the new battery. Is there a solution, short of the ridiculous expedient of recalibrating each and every time?

Hello, Your papers on battery technology are brilliant and open. In the article on Lithium batteries, it implied that as long as the maximum current and maximum voltage for the battery technology were not violated, the charge cycle did not really matter. Is that correct? Specifically, irregularly trickle changing should not be a problem, given the voltage and current constraints. Thank you for your excellent work!

Please help Im bought a music player or DAP(digital audio player) which doesn’t come with charger adapter it only had cable of type-C to USB to charging.i wanna ask some questions 1.if the device need 5V 1A is it good/safe if i using adapter that come with 5V 2A for long term?? I worry it will ruin my battery life 2.which the best method, buy an adapter and charge it with adapter 5V 2A or charge it using high end desktop computer with USB 3.1 which covered with UPS?? For more stable flow which is good to go?? 3.could you give me some good an adapter brand for my music player?? I just dont want take a risk for buy cheap adapter because the music player was not cheap and i want it be good as last as possible Thank you

I am using 15 numbers of 3.2V Li-ion cells to make a 48V battery. Plz anyone tell that upto how much voltage I need to charge my cell and battery to get 95 to 100% capacity.

Hi, Am clarifying the following things. 1) Normal charging current for Li-ion battery pack is 0.5C to 1C.Right? 2)If we connect the charger which can supply the current of 0.2C, Whether this battery charger can charge this battery pack?

Here is a problem. You can buy cell balancing circuits online (ebay, aliexpress), but why they manufacture these circuit boards with cut-off voltage of 2.4v? WTF

Hi, can someone tell me the best battery type for grid-connected application like MMC battery energy storage system. Is it Lead‐ Acid, NaS, Li‐ion, or Flow Batteries? thanks. Kenneth

Dear all, Maybe my question will sound silly but I would like to ask why we have to charge in constant current since we have a balancer? Kind regards, Costas Mel

Question from bike-owner not at all battery-expert: I have bought the 51913 LION-S battery from SHIDO for my motorcycle BMW R1200CL. Unfortunately on this bike the battery is situated under the petrol tank, so I first have to remove both side covers and the tank before I can reach the battery. Before buying this Li-Ion battery, I did not know that my “Smart” charger from CTEK (with trickle and desulfation mode) is not suitable. But if I have understood the manufactures charging instructions correct, I may use my old common charger that gives 13,2V and max 7A. QUESTIONS: 1) Is my old charger appropriate for my battery? 2) I cannot disconnect the battery cables from the bike easily (due to the location), does that prevent me from charging? 3) How do I know for how long time I shall charge my battery? 2-3 hours? 4) If I forget to disconnect the charger, will that damage the battery? Thank you so much for the answers!

For a 48v lithium ion battery with 3.2v/cell, after SOC 99% to become SOC 100%, why the voltage of some cells crosses 3.8v. What is the effect of cell voltages at float vltages. Please suggest.

I have planned to charge Li-Ion battery using dynamo. Will there be problem if dynamo fails to generate continuous power? Because dynamo is powered up by hand cranking and it is not possible to crank continuously to generate power. Every 20 secs once cranking will be stopped. Which means battery will be charged for 20 secs and left free for 5 secs(repeated in regular manner). Thanks in advance.

SAM, You need a simple BMS that will disconnect the solar panel when it reaches the maximum voltage. Look on ebay there are lots of systems out there. You can even get 18650’s with a built in charge chip that I think must shut off the charger when it reaches maximum voltage that might work for you. These 18650‘s a slightly longer as a result but might be a good solution for you. Do a search on ebay for BMS Protection Board for 1 pack 3.7V 18650 you will find it. Fred this might even work for you to and you would still be able to use the 5 volt charger

Fred you definitely need to get a proper charger rated for the battery.You will compromise the battery life and potentially cause other problems documented here and elsewhere.

Hello, There are much of good information here but please I need help to solve my issue. I have a RF remote system which is looking for signal at all time. It has one 18650 Lithium battery. I need to attach a mini Solar panel (I have a small 5v solar and a DC-DC converter set at 4.1v for charging) but I do connected this and remove the wire manually. How can I connect My small Solar panel to the battery and let it be, as I have mentioned the RF system is always working 24/7 listing for signal so the battery last about 6 weeks. how can I accomplish this. (to have a solar connected to one 18650 battery and solar will be working as long as there is a light and also the system will be draining the battery 24/7). Thank you ahead for helping me in this matter. I apologies if I keep repeating this as I have 6 of these systems and it get frustrating to do manual charge. Thank you, Sam

Hi, I have 2 devices that have different chargers, one is 5VDC 2 Amps, the other is 5.4VDC 3 Amps. I’ve been asked to investigate using the higher voltage charger on the lower voltage device. From what I have read above, it seems there is a risk of the battery exploding/bursting into flames. I would just like a confirmation that this is correct? We send these devices out to different customers, and if this is the risk involved we won’t investigate this further. Thank you.

Thanks Dan for the reply, the temperatures have improved and I think I have given the batteries enough time to charge. All of them have nicely come up to a full charge. I think they were all very badly imbalanced. You are right that zone between 3.6 and 3.7 is huge it takes along time to get to 3.8 at which point it rapidly reaches full charge. It is a big learning curve getting used to the nature of these batteries. I have been thinking about charging them in banks of 4 with independent 15 volt chargers and bms shut off. It strikes me that you would achieve better overall balance by managing in banks of four rather than having a single battery in a 32 battery pack determining when to shut down. That said I plan to have independent battery voltage read out’s as well as low voltage cut off. Any thoughts appreciated as I new to this.

Hi, you may damage your battery if charging in below freezing temp. http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperaturesou Well you get the most of the energy at about 3.6V. If you discharge it and look at the curve. it’s almost flat at 3.7-3.6V. In my experience dead batteries don’t take charge (or very small amount), sometimes they heat up, sometimes they just take the current and nothing really happens (they neither heat up, nor store the charge). Try charging that battery at normal temp and then discharging. 20h@5A it’s 100Ah, so it should be around 3.6V at half of the charge.

As per my previous questions, could I be experiencing some kind of self discharge, given that it is quite cold out perhaps I am not seeing a temperature rise in the cell.

I have 44 Sinopoly 3.6 volt 200ah Lithium batteries that I have bought slight used, less than 100 cycles for an EV project. I am going thru charging and testing them and the BMS that came with them. I have a few questions. I have manged to charge them in blocks of 12 volts with a car charger using the BMS as a shut off. The nature of the BMS is that the charging is shut down when one of the four cells reaches full charge. The temperatures have dropped to.5 to. 9 Celsius this week. Will that effect the ability for the cells to reach a full charge. The reason I ask is I have been charging one cell with a variable power supply that I think has a lower state of charge than others. I have charged it for probably close to 20 hours at about 5 amps and it has not gone much over 3.6 volts. The BMS is set to shut off at about 4.1 the batteries then settle back down to around 3.7 if fully charged. Should I expect the current to drop off if 3.6 volts is all it is going to get to or is it just very low and I need to just keep charging and expect it to rise to the full voltage eventually. The battery is not heating up. What I am wondering is what are the signs of an abused or failing battery in relation to charging. The literature mentions minimum charge rates of 3 percent of capacity is 5 amps enough for a 200ah battery.

@kenny thanks for your answers hopefully you still respond here or vince. Following on from my post from a year ago i got another Samsung replacement phone unfortunately from same factory which ships the phone with 0% battery. When i received it it would not turn on i had to charge it. I think the reading at 3% was 3500mv so 3.5v. What would you speculate the voltage is at 0% and also when it has switched off itself. My concern is this 1 was made in December 2015 so nearly a year it has been below 0% and switched off. How much damage is done to the battery long term kept in its sleep mode we are taking at least 8 months. Even if i get a replacement from Samsung or amazon it may be from the same factory which dont charge the batteries before shipping. Is it elevated self discharge the issue or OS it overall capacity? When i check the reading of my old phone which i need to send back the mv reading at 61% is 3920mv and on this new 1 3855mv ie sbout 70mv lower. Is this due to the storage at less than 0%? I assume Samsung protection switch cuts it off around 3400mv 3.4V and i know letting a battery drop to that low voltage that it switches off is bad even if you charge the next day but if you let it dwell at that in an shut down off by itself state for months how much serious damage is there? importantly how do i tell? I have to send back the other one in a week or this 1 and cant decide which to keep. I dont want a battery which will screw up in a few months because some idiots in fsctory didnt charge it before shipping like they are supposed to Is the biggest issue welf discharge or overall capacity? Reading all the lithium articles it doesnt exactly explain my situation just that if you didcharge to 2.5v frequently ie recharge quickly after the self discharge is only 8mv per day conpared7to 8mv for a new battery. There’s no info on one which has been left in low voltage state of 3.4v then recharged months later. It only says copper dendrites form below 2.5v and the example they used they shorted the battery but ran it down to 0 volts. Mine hypothetically shuts off at below 3.5v dependion samsungs protection switch. Would the damage be significant? I can’t replace it it’s non renovable

Does anyone know what would happen to a Samsung phone which has 3000mah battery but was shipped with 0% battery and subsequently was stored in storage in warehouse for a year and the protection cut off switch was activated so did not turn on upon receiving. I think the voltage was around 3500mv so 3.5v at 0% maybe a bit less say 3.4v. how much damage to the lithium ion battery would their be if it’s been in storage at low voltage for a year brand new? Trying to decide whether to send it back. The voltage for my previous phone which i need to send back at 61% battery is 3920mv so 3.92V but on this one (due to damage i suspect of being stored at 0% and sleep switch activated ) at 61% reads 3855mv (3.85V) is the difference of 70mv 0.7V a significant difference?

I am designing a Li-ion charger for a product and will be using a purchased charger IC from a major IC manufacturer. It has the expected precharge, constant current, float voltage phases. I have a limited power source available, so my question is, is there a down side to providing a low current during the constant current phase, like C/20 (other than longer charge time)? Thanks in advance

I have been commissioned to design and supply the electrical control for a 38 foot electric boat that needs to run silently for 2 hours at 6 knots. The total power required is 70 kW. Light weight batteries is essential. I am assuming Lithium Ion. I have the ability and experience to produce the intelligent battery charger for lithium ion batteries. Where is the best place to purchase the batteries.

I have a battery pack, 6-cell (each cell is 3.7V/2500 mAh) making it to a 22.2V battery pack with protection circuit. I connected to 2 battery pack 22.2V in parallel so that it becomes a 22.2V / 5000 mAh battery pack. What sort of 22.2V battery charger should I use? There is a choice of: a) 22.2V / 2Amp battery charger b) 22.2V / 4Amp battery charger Can anyone advise? Thanks ERIC

Get a question, for figure 3. since you first use fixed current then fixed voltage, how to do you calculate the C-rate to be 1C?

It could be a good choice to use battery until 40% of charge then charging it up to 80% and then reuse it? If i’m using the laptop during the charging phase i not good? Thanks! 😀

I’m using a battery pack composed of Li 18650 Cells. Although the cell data sheet says the maximum battery voltage is 4.2, the BMS manufacturer suggested i define the cell termination voltage to 4,1. Is there any problem or advantage on this ? As i see it it will be safer and since i will be working from 85/90 % SOC to 30% it will prolong the batteries life? Am i right ? Thanks

Hello everyone. I’ve got a question. I have an electric scooter with the lithium ion battery (72V 20Mah). Can I charge it with a charger for lead-acid batteries?

The previous termination point of 4.2 V (chemistry dependent) is unchanged. What’s with the spam posts above? If these Комментарии и мнения владельцев aren’t moderated at least provide a report option.

As long as the batteries in parallel are the same chemistry, and (as you state) are about the same capacity, then you can do this, and it will add the capacity ratings. This requires a modification to the charge termination though, as the previous termination point no longer applies with the higher capacity. capacity (900mAh vs 500mAh) results in more hours of run-time. that is what mAh means. how many milliAmps of load for how many hours.

Hello I have a question what happens if I connect 2 batteries in paralel 1) 500 mAh 3.7 and 2) 400 mAh 3.7 v. do I obatin more capacity or more or less 900 mAh, or more hours ? Thanks

Hello. My question is this: If I charge Lithium Ion battery non-stop with 10mA, that is 24/7 with no cut, will this damage the battery? Charging time can be weeks, no problem; my concern is that is this going to damage the battery somehow?

@Dan Thank you for the reply! As you said, there is some shortening of battery life but I haven’t seen any document on how much.

@Byron Hourmand if you’re thinking about long-term effects, then mostly yes. As it said earlier, lithium batteries don’t like to be neither in a fully discharged state, nor in fully charged. I cannot tell the numbers, but you’re shortening life of a cell while continuously putting it in a fully charged state. This is my 5cents. (that is the reason why my laptop battery is absolutely dead after 4 years)

Would a LiPo battery get damaged if after the switch from CC to CV, the CV (4.2V) is not terminated after battery is fully charged? Your reply is appreciated.

@ Andy, are they in parallel or in series? In parallel no issue as they will always be balanced. In series you can take them out every 10-25 cycles and charge them separately, if soldered together best is to add a small BMS Battery Monitoring System setup which equalizes the voltages of each cell, depending on how much current is needed the vary, some examples, search for 2s BMS 4A on eg. aliexpress.com.

If my pair of 18650 batteries become unbalanced how do I get them back to proper balance? They’re LG HG2 3000mah 18650 cells. They’ve been married since day 1.

could you any one can tell about how the lithium ion battery full cell making ? how much cathode(LiCoO2) and how much anode(graphite) we have to take to fabricate the 250 mAh cell. what parameter i have to take care of when we make full cell. the cathode specific capacity 160mAh/g and anode is 370mAh/g ,so that which one we have to considered when we make full cell fabrication.

i have changed my laptop battery since 6 month ago with a new one it was working very good then amount of the charge reduced to 3/4 of full charge and its about 3 month battery not charging and condition of the battery are good i have changed the battery with the similar one of my friend it was charging without any problem for your more information my laptop le z500.45ip Lenovo and the battery li-ion color black voltage 14.4v capacity 2200mAh thanks in advance mohsen.m.shabestari

hi. i bought a Chinese quad-copter phantom 5c from a local store.i charged the battery for 3 hrs but charge-full led never lit. it use to fly for two minutes before emptying the battery.i got its battery replaced from the same store. it came with a USB charger that plugs into wall socket and reads SEC: 3.7v. 350mA. the a wire with a USB(and a small circuit on it with a charge=full led) plugs in USB port of charger and other end of wire has a connector that plugs into battery(connector). the new battery reads (ds 852540) 3.7v 650mAh. NOW THE QUESTION IS THAT HOW LONG SHOULD IT TAKE TO FULLY CHARGE THIS BATTERY WITH ABOVE MENTIONED CHARGER ANOTHER QUESTION IS THAT CAN I PLUG THE USB WIRE INTO MY LAPTOP.

This is a great post about Li-ion batteries, and I would like to learn more. Does anyone reading this post know much about these new Hover Board / Self Balancing Scooters that have rechargeable Li-Ion batteries and have been catching fire or exploding during charging or during product use? These scooters are made primarily in China by a number of different manufacturers, and I’m sure the quality of components and assembly differs. The more expensive scooters come with Samsung or LG brand Li-Ion batteries. The cheap ones have Chinese made batteries. Is a quality battery one of the main contributing factors to prevent the problems of over-heating / fires with these products? Or is it also a matter of the charging adapter unit that is included? Do the charging adapters have circuitry inside to prevent overvcharging of the battery? The ones I have seen have red and green lights. red means charging, green means charged. Would green light mean that the current from the charger is stopped, because the battery is charged? Or do the scooter units themselves, or the batteries have built in circuitry to prevent over charging? I was thinking of buying one of these products for my daughter for Christmas, but would like to knowledgeable about the risks.

Thanks for a superb insight. Wanted to understand this better so ran some elementary tests Can you help me interpret the results and answer the questions raised here please http://engineering.stackexchange.com/questions/6406/charging-a-smartphone-battery-while-using-it/6409#6409

Does anyone know what would happen to a new 3000mah mobile battery that was stored in warehouse for 3 months at 1%? Asw we know from here high voltage heat and low voltage ie stored below 5% are very bad for the battery capacity. Would i notice this issue straighr away? The battery is sealed in the new phone and cant be removed. How much stress and capacity loss would be caused if such a new battery was stored at 1% for 3 minths? Are we talking a 10-20% reduction in capacity overall? It seems fine but im just worried in a couple months it’ll kick in and my battery wont last as long as it does now as i just got the phone.

I see several unanswered questions. I can try to answer some of them: 6/8 Richard: Good question. I haven’t seen any info about charging efficiency for li-ion batteries either. Post back here if you’ve found any. 6/10 Danigar: Charging while the device is on can full the charging into thinking that the device battery is at a lower voltage than it really is, so I think it matters most when you are near full. It also depends on how much current the device is using. That said, I don’t turn off my phone when charging either. 6/10 Tam: Was this after the battery was fully charged (no more current going into the battery)? I think that older batteries will drop in voltage quickly, but should start full. Not sure why yours doesn’t. 7/6 roya: It sounds to me as if your battery just isn’t holding a charge. Check for weak/diluted electrolyte? 7/15 Robert: Li-ion batteries can normally be charged in any position. lead-acid and liquid batteries need to be charged upright to allow for potential venting during the charge process. 7/28 Pushpendra: Sorry, don’t know the answer off-hand. 8/24 Abraham: A fully charged Li-ion usually attains ~4.2v when new. Your battery starts off with a lower voltage which means a shorter life. It’s not truly dead. A Li-ion battery at 1.0 volts needs to be recharged, it’s dead because it can’t provide much current at that voltage, but recharging it will bring it back to life 10/1Vivek: For max battery life, try to keep the charge between 20-80%. Do not let it discharge completely. If charged 100%, try to use it immediately. 11/2 Taxiarchis: 1) So long as the fast charge does not exceed 0.8C, it should not damage the battery. Fast charge might end up over-charging slightly. 2) The device itself should limit and regulate the charge voltage, so the 5.0V USB voltage is converted to ~4.2V by the device. If you are feeding the 5.0V straight into the battery, it can overheat and explode. Some 18650 cells are protected against this, but others are not. 3) I haven’t seen any responses from the author in a long time.

here are my 2 or 3 questions, 1) Is slow charging (via USB-Port) better then fast charging (wall plug)? 2) USB chargers have an output of 5.0V. Would this cause problems with lithium batteries since as stated above, charging above 4.3v causes plating of the metallic lithium on the anode? 3) I don’t see any Комментарии и мнения владельцев replied. You reply via email, or don’t? Thanks!

really a good informative and educative article i have gone trough it really gave real picture of the LI-ion batteries and charging modes thank you

I recently download an app which I think could be really beneficial for lithium-ion batteries in mobile phones! This app called ace charge, it disconnect the charge on 100% full charge or even can define to not charge the phone over 80%!

Hello everyone I manage a small wireless business in south Fl I hav been following an excellent way of charging Li-ion batteries and passing it over to my clients Lithium-ion Batteries Should be turned off charged Up to 5 hours before their first use. Ignore the phone or dock charger telling you that the battery is Full—this is Normal but, is not accurate if the battery is not initialized. Battery life varies by use and configuration. DO NOT fully discharge a lithium-ion battery! Below 8-10% Unlike Ni-Cad batteries, Lithium-ion batteries life is shortened every time fully discharge them. Instead, charge them when the battery meter shows one bar left. Lithium-ion batteries, like most rechargeable batteries, have a set number of charge in them. ONCE INITIALING YOUR BATTERY: BASIC Handset Within 2 Hrs MAX. OR Smart Handset Within 3 Hrs a partial charge is better. OVER 3 Hrs OVERNIGHT CHARGING, Talking, Playing while Charging WILL DAMAGE YOUR BATTERY CELLS. And they work Awesome- Hope will work for you as well.

I am HAVING A QUESTION. I have a battery that i use to charge it with a 10W panel. the BATTERY IS 3.5 fully charged, a lithium ion battery. nut what makes it a dead battery?? when it turns to 1.0v?? when i recharge it with the panel it turns 3.5v and i can use it again. BUT MY BOSS TELLS ME ITS A DEAD BATTERY WHEN IT TURNS 1.0V

Hi there, I have two questions. if anybody can help me to understand: 1. Why we use Cu for anode and Al for cathode as current collector ? 2. how to select a voltage window for a full cell (Li-ion case) while using different anode. Suppose if I am working with Graphite half cell/anode the voltage window to test the battery is 0.0-to 1.5 V. Now if I have a Full cell with LFP/LMO/LCO as cathode and Graphite or Si or LTO as anode than how to select a voltage window to test the battery ?? If anybody there can help ?

Does a lithium battery used in a golf cart need to be horizontal for charging or is vertical ok.(the space where I store the cart needs to have it vertical)

I`m working on solid electrolyte using Graphite as anode and LiCo2 as anode. My battery does not provide a reliable Constant current charge/discharge cycle. it takes less than a minute to charge the battery to 4.2 v at constant current rate of 0.2 mA and also very short time of around 10 seconds to discharge it from 4.2 V to almost 3v. However, the constant voltage charging process period ranges from 1 hour to 2 hours which means the battery hits the saturation voltage. my question is what can possibly contribute to unsuccessful constant current Ch/D-Ch cycles?

I really like your page. I want to ask where can I find a catalogue with the discharge characteristics depend on time. I have looked everywhere, but I can only find for lead acid. thank you and congrats for your work.

Hey guys, I’m currently using a Li-Ion charger IC(MCP73861) to charge an old 18650. I have set the charging voltage at the “saturation charge stage” to 4.2V but the battery voltage seems linger at around 3.9V on my oscilloscope/data logger. I know that an old battery may result in reduced capacity but can the same be said for the voltage?

Hi there! You say A device should be turned off while charging. This allows the battery to reach the threshold voltage unhindered and reach a low saturation current when full. A parasitic load confuses the charger. Could you be more specific as to how important this is? Turning the cell phone off and on every time you charge it is cumbersome, so unless it has a considerable impact on battery life I would rather not do it. Thanks!

I have read everything I could find on charging LiPos, but there has been no discussion about the charging efficiency, i.e., what percentage of energy put into a cell goes toward actual capacity? I know that lead acid is about 80%.

Sorry, haven’t checked here in a while. Here are some answers that I have: 3/5: mert: The time to charge depends on the amount of current your charger can provide, and the initial state of your batteries. Li-ion batteries should be shipped with 40-60% charge. Assuming that your batteries are about 3.7V to start, then the charge time will be about 1 hour at 500mA, or 1/2 hour at 1Amp. 3/6: DJ: Yes, the 3.7V is just a nominal voltage for a Li-ion battery. Charge at 4.2V for a full 100% charge 3/18: Christian: Max charge rate is usually 1C, or 1.43A for your battery. Recommended charge rate is 0.8C or 1.144A. So for a fast charge, you can use 1A max. 500mA would take longer, but may be a bit better/safer. 4/8: Mina: I assume that your tablet has a Li-ion battery. For maximum life, start recharging at 20% and stop at 80% for maximum life. Thus, it’s OK (and better for the battery) to recharge before it is fully empty 5/2: tim: Sorry, that’s not quite enough information. The battery pack capacity rating (in amp-hours) is needed to determine the recommended charge rate. If the pack is rated for 0.75AH (or 750mAh) then the 0.6A charger should be OK. I suspect that it will be fine, as most packs are designed to have larger capacity. 5/19: Martin Butcher: Sounds like a myth, but it depends. If the solar power is converted into standard AC voltage and the phones are charged with a regular charger, then it shouldn’t affect the life of the phone battery any more than regular power would. If the solar power is fed directly into the phone without regulation, and the voltage varies, then it could reduce the life of the batteries (or more likely damage the phone). 5/24: tom: With a 9000mAh pack, the charge rate of USB vs. 1A vs. 2.1A should not affect the battery life at all, the max recommended rate of 0.8C is 7.2A! It must take a really long time for a full charge using a USB port though!

ijust bought a 9000 mill amp battery pack for my phone it had no charge when it came out of the box charging with a 2.1 amp charger it charged a bit quicker then expected but its charging so this battery can only get a slow charge due to the limits of USB but would a 1 amp charger be better for longer life or would it not matter

Very detailed explanations. I have built a few Charging systems myself and the information you supplied gives a good insight on do’s and don’ts. Thanks

a query than a comment. I am currently living in Malawi where there has been a variety of programs providing solar panels in villages. Somebody with electricity can charge about 10cents to charge a phone, however I have just heard that people are avoiding getting their phones charged with those that have solar power on the grounds that solar charging reduces the lifespan of the phone battery. Does this sound realistic, or might it be a myth? ( possibly promoted by those who are wealthier and have mains electricity connection)

Hello B.U. / kenny, I have a device (portable amplifier) that claims to use a 4-pack li-ion. The original charger of that device is a 3P10-L1016. Output: 16.8V 0.45A. My question is, can I use the same model 3P10-L1016 but with a different amperage? The replacement charger I found has rated output of 16.8V 0.6A I really need help on this as I don’t want to make a mistake and destroy the amplifier. Thank you!

Should i make sure that mysamsung tab4 baterry fully empty then recharge it or is it ok to charge it even if its not fully empty. Thank you.

hi, i have a 3.7 v. li-on battery 900mAh 3.33Wh how many hours do i have to do the first charge of it ? thanks

@Christian: For a 2400mAh, the 1C rate is 2.4A. The maximum recommended charge rate is usually 0.8C, or 1.92A. So I would not use anything greater than 1.5A just to keep a little margin. After that, it’s just how fast you want to recharge your battery. At 1.5A, the battery will recharge in less than 2 hours. 500mA will take ~5 hours for a depleted battery.

Hello guys, I’m buying a smartphone that does not bring original charger. The battery is 2400mAh li-ion. I wonder how many amps have to take the charger to extend the useful life of the battery, if low amp (500mA, for example), or a high amperage (1A-2A). How many amps should I buy? Regards!

Here are some answers that I believe are correct: 12/28: James: It would be dangerous to apply voltages greater than 4.2V. I would FOCUS on the charging current, and limit it to 0.8C max. I agree that it is difficult to measure the battery voltage while charging. Even though the internal resistance of the battery is low, the voltage will still be elevated slightly compared to the actual voltage of the battery. 1/4: Jerry Jones: Apple suggests doing a full discharge/full charge cycle once a month to calibrate the percentage of battery life indicator. This process will shorten the overall life of the battery, but once a month should not affect it significantly. 1/4 Ryan Evans: About the same for charging in a phone vs. a charger, depending on the charger. However, in a phone that is still powered on, that may be a little worse since the charge circuitry could get confused with the power draw from the phone. So maybe the separate battery charger (if it’s a decent one with proper voltage control) would be slightly better. 1/8: Nancy: The country of the charger shouldn’t make a difference so long as the outputs are correct. Just make sure that the output voltage of the chargers match. The country of the batteries shouldn’t matter either, so long as they are the same type. 1/12: petey pablo: Unfortunately, I don’t see any answers from Vince here for a while. I agree that the difference in the percentage of run time reading is a calibration issue. The discharge voltage for Li-ion batteries are fairly flat around the 3.7V range, so a very slight difference in voltage could translate to a significant percent of run time difference. 1/19: Ankit: Charging to 100% and discharging to 1% is stressful to the battery, and will shorten the overall life of the battery, but it will (obviously) give the longest time before recharging is necessary. If you can, I would charge from 80%-20% to prolong the overall life of the battery. Even reducing the span to 90%-10% would help. Most people care more about how long their phone run between recharging since they change phones (or batteries) once performance drops. 2/1: danimal: The amount of current flow follows Ohm’s law, I=V/R, where I is current in amps, V is voltage difference between the source and destination batteries in volts, and R is the resistance in the circuit (both internal to the batteries and external to the batteries) in ohms. You will need a series resistor in the charge path since the internal resistance of batteries is typically very low. The resistor would be R=(Vs-Vd)/I where Vs is the voltage on the source battery, Vd the voltage on the dead Li-ion battery, and I = 0.01A to 0.02A. This is assuming that the internal resistances are small. 2/1: James: good point. I think that this article refers to the most common Li-ion battery formula, Lithium Cobalt Oxide(LiCoO2). I believe that the basics still apply to other Li-ion technology (don’t operate continuously at full charge, don’t fully discharge) but the specifics (charge voltage, max voltage, charge current) may vary. Hope that you all check back to see these answers!

Does all of the information contained in the original post still apply? I’m thinking that battery technology may have changed and improved since it was written.

i’ve heard you may be able to recover a dead lithium cell by charging it with very low mA, like 10-20 mA until it comes back up to around 1-1.5 volts. can this be achieved by hooking up a 1.5 volt alkaline battery (or several) into them? if so, how do you calculate mathematically, how many mA the aa/aaa battery will shoot into them

i hav moto x 2013 which has a 2200 mah li-ion battery. i usually charge it upto 100% the use it till 1% ans repeat the process every day after reading this matter above ,i am confused can any1 help me by telling how to charge it.i mean frm what % till what %

@vince I recently got a tablet with a 9500mah battery I also still have my phone with 3000mah and a spare with 2100mah.my confusion is that I followed your advice to charge it when it drops below 3700mv which is around 25% on my 3000mah battery and 32% on my 2100mah one. My confusion is that on the massive 9500mah tablet battery it reaches 3700mv at only 45% battery. Why is that.is it a calibration issue?

I bought my camera with 3.6 v lithium ion battery in Korea. I will be moving back to Canada. Can I charge these batteries in a Canadian charger that I will purchase when I arrive home? If not, do you thnk the camera will function the same with the same type of battery bought in Canada?

Is charging the battery fully in a battery charger better than charging it in the phone or worse or about the same?

Apple suggests to fully cycle (fully discharge/fully charge) its batteries once per month. This suggestion seems to fly in the face of the points made in this article. Who’s right?

I am now trying to design a Li-ion battery charger and facing 2 questions about charging a Li-ion battery. 1. Is there any maximum charging supply voltage for charging the battery? It seems that it is dangerous if I apply 10V to charge the 4.2V battery. Or should we only FOCUS on the charging current? 2. The paragraph states that the maximum voltage of most of the Li-ion batteries is 4.2V. How can we measure voltage when we charge the battery? The battery emf ( that means the open circuit voltage) to voltage across the 2 terminal.

Thanks for the clarification. I may as well take the opportunity to add a note on the Li-polymer batteries I was playing with that mentioned in my first post. The brand-new (8 year-old!) battery when left charging overnight on 4.2v @ 100mA was drawing zero current next day, so fully charged. I stuck it on a small 12v motor that draws at least 100mA, which continued to spin for at least 11 hours. so the battery would have delivered its full rated capacity of 1260mAh. Having done this a few times now with 2 of these same batteries, one a well-used one from an old mobile phone, what is immediately obvious is that protection-circuitry is built into these batteries. when the voltage drops to 2.50v, it is switched off completely, dropping to zero volts. This to me reaffirms how crucial it is with Li-batteries that the voltage should not fall below this. I am also very impressed that even after sitting for over 8 years, these Li-polymer batteries both immediately accept a charge, and deliver their rated-capacity back to a load. I also have (many) 3.6v NiMH batteries of the same age. While most were also brand-new then, many have ‘leaked’ badly in the interim. The ones I tested did take a charge though, and delivered close to their rated capacity. However, their being charged only exacerbated the leakage problem, which they continued to do even after several charge/discharge cycles. So, personally I think Li-batteries are a far better technology than NiMH, especially long-term.

My comment was only to suggest that C (when referring to C-Rate) was possibly being confused with degrees Celsius only because the writer refereed to temperature directly following the statement about C-Rate. Anyways. I think I just added to any confusion that may have been present in the comment discussion.

Brad T, that post of yours is really opaque. on the one hand you seem to agree that the reference to C has nothing to do with degrees Celsius and actually refers to battery capacity. but then you write; The following statement involving temperature is has no relation to the C rates which is meaningless, if only because nothing follows that line! Or was that line meant to read The following statement involves temperature and has no relation to the C rates Either way, nothing followed.

RE: “Manufacturers recommend charging the 18650 cell at 0.8C or less. “ C in the article refers to a unit of measure based on the capacity of a given battery. A 1000mah battery would have a C rate of 1000ma eg 1 C = 1000ma.5C = 500ma The following statement involving temperature is has no relation to the C rates.

Well caught battery Bro! I am now wondering just how ‘authoritative’ this article really is if the author actually believes that the manufacturers are referring to temperature! This is a real rookie-mistake to make.

How to charge Li-Ion 3.7V? I’ve a iMAX B6 Pro charger that assumes Li-Ion cells have a nominal voltage of 3.6V and Li-Po have a nominal voltage of 3.7V. I’m going to charge some 18650 cells taken out form some laptop battery pack. They are marked as Li.Ion but with a nominal voltage of 3.7V. Now, how should set my charger? According to the chemistry (Li-Ion 3.6V) or to the nominal voltage (Li-Po 3.7V) In the firs case i’m afraid to charge the cells not completely, in the second case i’m afraid to overcharge the cells with the risk of fire. Please help me to understand what to do. Thank u very much!

One thing to note. the article states Manufacturers recommend charging the 18650 cell at 0.8C or less. Actually manufacturers require charging the 18650 cell ABOVE zero degrees Celsius. The 0.8C is a simple a way of to talk about charge and discharge rates for batteries.

what will happen if a LI-ion battery continuously charged without unplug the charger?? Even if you have continuously connected the charger the charger is Smart enough to not to charge the battery once its fully charged. There is nothing wrong in keeping battery always connected to charger. Infact laptops which are being used in home are almost always connected to charger. the only harm is that Lithium batteries don’t like highest and lowest allowed voltage level. So even its safe to constantly keep the battery at full charge the rate of deterioration of battery is higher compared to keeping the battery at about 40% charged. But then its not possible to maintain the battery charged to 40%. 2. What happen if the battery charged and use for some. There is absolutely no problem in doing that every time. In-fact it will increase your battery life. Remember cells dont like extreme high or extreme low voltage. Only problem is that the state of charge (SOC) calculator will slowly drift away and will show you wrong capacity remaining values. They correct themselves each time the highest and lowest voltage level are reached.

i want to know what will happen if a LI-ion battery continuously charged without unplug the charger?? also what happen if the battery charged and use for some time again charged after some time without discharge the battery to the minimum charge(not only one day,all times doing this ) so any problem??

I am interested in buying Li-ion 9v batteries but was taken aback by the large numbers of Amazon users that ended up with dead batteries from allowing the voltage to drop too low. I come across this all the time with NiMH batteries with my expensive charger where the voltage is too low to register with the charger, so it never initiates a charging-cycle. The solution is just to stick the ‘dead’ battery on a cheap charger that always supplies a constant voltage supply and the battery soon comes back to life! I figured this was the case with Li-ion batteries also. until I came across this article! This piqued my interest enough to dig out a few brand-new but very old mobile phone Li-polymer batteries I have. over 8 years old but never used still enclosed in their plastic shrouds. Sure enough, the measured battery voltage was zero. Setting my bench power supply to 4.2v and limiting the current to 100mA, I connected up the ‘dead’ battery and straight away it started to charge! It has been charging for several hours now, the voltage across it slowly increasing (it’s about 3.9v now). due to the power supply’s current-limiting. and I have no doubt that I will end up with a fully charged Li-ion battery. So I don’t know what to make of this article now. or the scores of Amazon buyers that have ended up with ‘dead’ batteries.

As stated in the article its best not to fully charge and fully discharge the battery which is very much known fact and logical, so I want to charge my 4.35V LG D1 (3000 mAh) cell to only 4.1V. I want to know should I just charge it to 4.1V in constant current mode and then disconnect the charger, or should I charge it to 4.1V in constant current mode and then keep 4.1V in constant voltage mode till charging current tapers to a small value? What is better for cell? Is there any advantage or drawback of any method?

As stated in the article its best not to fully charge and fully discharge the battery which is very much known fact and logical, so I want to charge my 4.35V LG D1 (3000 mAh) cell to only 4.1V. I want to know should I just charge it to 4.1V in constant current mode and then disconnect the charger, or should I charge it to 4.1V in constant current mode and then keep 4.1V in constant voltage mode till charging current tapers to a small value? What is better for cell? Is there any advantage or drawback of any method?

I have LG G2 mobile phone purchases from korea. My battery removable Li-ion of 2610 mah. My mobile battery is not working properly from last many days. Many time i used data cable for charging my mobile. I have 1.0 Amp mobile charger, Please tell me what is the right procedure to charge my mobile. Please tell in steps. I want to change my charger by 1.5 amp or 2.0 amp. Which one is good for my mobile battery.

idn’t know that my phone was like 40% then when i got on the bus it was 90% aka this is from 10- 17-14 i am ijn 6th grade btw

I have purchased a new lithium ion power bank. There is some partial charge that it came with. Should I first discharge the battery completely and then charge it fully or should I first charge it completely and then start using?

I have a cycle light supplied with a 8.4 volt 6400mAh battery pack. the supplied charger has an output voltage of 4.2 volts at 500 mA. the battery refuses to charge. am I missing something or is it obvious. I am a graduate electrical engineer

hello to all of you i am design a AC to DC charger for the USB devices. so in this when devices(load) is connected then and then charger is work otherwise not work. In short i am saving a enrgy is it possible. If it is possible then which circuit is used for the load detector.

hello, i am design a AC to DC charger for USB devices. And i am some query about that. My requirement is the when only device is connected then and then charge otherwise this circuit is off. in short i want to save a power when the device is not connected

I have purchased Lithium PO4 batteries. Each battery is rated at (3v-3.2v-3.65v) 20Ah-60w What would be my charging v outputs from 60 to 85%? Thanks, Gary PS- The BMS is the Ligoo the Battery pack will be a 400Ah. The charger is a TCCH-4k input is 240 @ 8.1 amps

Hello, What if I charge my iPhone in an interrupted way ? Let’s consider this pattern: 20 seconds of charging and 60 seconds of pause. All this for a half day or so. Will that affect the battery ?

Hello, Will frequent interrupted charging of phones (or so) affect its Lithium-Ions ? Let us consider this constantly repeated cycle : 20 s of charging 60 s of pause for a half day.

I bought a new li-ion battery for my smartphone xolo q1000 it was well charging on the 1st day but the next day how much ever I charge its not charging at all.why is this??

Can a 12 volt lithium ion rechargeable battery be used to charge the 3.7 volt battery in a cell phone?

My mobile is a Cynus E1 (Mobistel), has little time and I’ve noticed that the percentage that tells me to be on the percentage is different when I turn it off to charge. Arriving at 15% I turn it off, I connect and gives me a 50% !! Not always gives me these incorrect percentages. I’ve calibrated following the steps of the video, by the way, excellent video and for several days it looked like it had been solved. I usually do not complete charge and discharge. I usually do loads of different percentages, 44%, 60%, 15%. according to the occasion. That if the phone does not turn off but it has me a little worried. I have entered into some forums and there are people with the same problema.Mi question is: Will faulty battery, has a solution. Thank you

please someone give correct info about using new lithium ion battery for the first time. i am very confused about this as everyone has different opinions

Hey sir i need your help!!AS i am using a phone now a days (sky vega 850) and it’s battery is Li-Ion 2600 mAh battery now i lost mine original charger now can you guide me which type of or i should say which type charger that contain how much ampere should i used. i need your comment as i am little bit worried about my phone Thanks

Hello, I want to ask a basic question about charging process of multiple batteries at same time. For example if I have connected some lithium cells of 4v in 5s3p. Now if I used them 50% then after start charging the whole circuit with one charger what happened? Do they get charged one by one in a circuit or all will charged at once with same voltage increment. thanks in advance

Hello guys I have carefully studied this website about lithium ion batteries, i wanted to know if HD gaming on smartphones reduces battery life since high demand gaming applies high currents to the battery (usually more than its nominal capacity) and very rapidly drains it. does it highly affect cycle life? should i stop playing high quality games on my smartphone? thanks in advance,

@Kathy: you cannot destroy such a battery with the standard charger, even if you leave it in for 24 hours. The problem you have must be with the flashlight itself. I hope they didn’t tell you otherwise in the shop.

@vince I was hoping you might be able to shed some light on this battery situation I’m having, judging by the information above in the article temperature makes a huge long term impact on battery life i.e. above 30C is detrimental. it’s summer here where i am and even though the temperature is only 20C in my phone the battery temperature is usually in low to mid 30C’s (unavoidable really, even in an indoor air con place) and i’ve noticed a dramatic drop in my battery life judging by the voltage. a few questions I have is. if the temperature is high therefore i’ve lost overall capacity in the past 2 months. ie usually i charge at 30% with the voltage reading higher than 3795mv and above. but recently i’ve looked at the battery info at 30% it now says 3700mv or below. im using same charger charging same way the charger which came with the device. would it be plausible that the heat has reduced my overall battery capacity? something you mentioned before that the speed at which the charger chargers the phone affects how much voltage reading there is. i.e. if it fasts charge with the charger then obviously the run time wont be as long. however it’s the same charger charging the same way as before. is the only explanation that the heat has reduced the capacity overall? bear in mind i do not charge it to 100% often as it causes stress on the battery so that can be ruled out. i used to be able to get by around 80% battery but now these days i cant seem to get through a day with that much. i.e. when i charge again at 30%. is it plausible that (ruling out that i dont let it drop to zero, always charge at 30% and lowest 16% once in a while) and never charge to above 93% (only once in a while) mainly always take off at 70% cos it takes so long to charge i get impatient. that effectively my battery capacity has reduced dramatically? i only got it in march manufacture date was jan 2014 and it’s only been warmer the past 2 months and that’s when i’ve noticed the dramatic reduction. the annoying thing is there’s nothing i can do as there’s no fan to keep it cool, i already keep the case slightly open to let the hot air escape. and also it’s incovenient being unable to use the phone when there isnt a fan source. is that probably the most likely explanation? it seems due to the higher temps i’ve lost 10% overall battery capacity (assuming the reading is correct and it is not charging faster than normal) consequently. if the overall capacity reduces does that therefore mean the phone should charge quicker to reach 80%? i assume that’s how i’d know if the capacity has been reduced noticeably.

@Khairul: your new mains adapter has 5V instead of 5.25V. So it won’t harm the battery or the charger circuit inside the phone. Worst case, your battery won’t get fully charged or won’t charge at all if 5V is too low for the charger circuit. Your max adapter current 1 amp is no problem. The phone will never draw that much out of it, so you have some spare. Andre

Kathy, seems to me this is a flashlight problem, not a battery problem. The light works when you unscrew the cap a little bit. I think your battery and charger are OK. Maybe tightening the cap puts too much pressure on parts inside the flashlight. Andre

Hello, I have a battery 1S4P Li-Ion 3.7V 8800 mAh (4 cells of 2200 mAh in parallel). I have a station charger model ELV ALC8500 Expert 2. I have charged the battery yesterday in conditions C/2 in CC ( Constant Current step, 4.4 Amps of charge current), then max voltage when CV step (Constant Voltage) equals to 4.2 V. I have started the charge, then stopped it as needed to get back to home. When I stopped it, it was entered in the CV step, but wasn’t finished (not yet arrived to 0.03 Capacity conditions). I wanted to restart the process this morning, to finish the charge, but impossible. When i read the voltage, it is indicated 1.8 V, meaning the battery is dead. I really don’t understand what happened. The battery was disconnected, in a closed plastic box, with good temperature. Does someone has ever met this case?

On December 2, 2010 at 1:12am Steve Webert wrote: Does it benefit a lithium-ion or lithium-ion-polymer battery to periodically discharge it “fully” (ie, down to the above me.ntioned 2.7V-3.0V range)? I have read several OEM’s offering differing strategies for optimizing battery life. Thank you for your time and efforts—I very much appreciate the above instruction. DUDE, what the hell!? READ THE ARTICLE. NEVER ever ever, NEVER let a LI-Ion get anywhere near below 3.0v for any period of time, to do so renders your battery useless. 3.2v to any device, means ZERO, I turn myself off now, no matter what, thankyou for using me. (That’s the device talkin’, yo!) READ THE ARTICLE.

quote: Before prolonged storage, apply some charge to bring the pack to about half charge. But my Canon S90 camera’s manual states that to store the battery for long periods, deplete and remove it from camera. Storing a battery for long peroids without depleting may shortern its life. (The camera shipped with a Li-ion battery. NB-6L 3.7V 1000mAh) So I’m really confused. Which should I believe, the manufactures’s manual or this article?

quote: Before prolonged storage, apply some charge to bring the pack to about half charge. But my Canon S90 camera’s manual states that to store the battery for long periods, deplete and remove it from camera. Storing a battery for long peroids without depleting may shortern its life. (The camera shipped with a Li-ion battery. NB-6L 3.7V 1000mAh) So I’m really confused. Which should I believe, the manufactures’s manual or this article?

quote: Before prolonged storage, apply some charge to bring the pack to about half charge. But my Canon S90 camera’s manual states that to store the battery for long periods, deplete and remove it from camera. Storing a battery for long peroids without depleting may shortern its life. (The camera shipped with a Li-ion battery: NB-6L 3.7V 1000mAh) So I’m really confused. Which should I believe, the manufactures’s manual or this article?

quote: Before prolonged storage, apply some charge to bring the pack to about half charge. But my Canon S90 camera’s manual states that to store the battery for long periods, deplete and remove it from camera. Storing for long period without depleting, may shorten its life. (The camera shipped with a NB-6L 3.7V 1000mAh Li-ion battery) So I’m really confused. Whom should I believe, the manufactures’ manual or this article?

@vince thanks for your reply. you mentioned before that ideally it be best to charge the battery when it reaches just below 3700mv and stop charging just after it reaches above (which is impractical of course) as i have a 3000mah battery, what % level of charge is left when it reads 3700mv? and what does this article say is the best mv to not let it drop below when you start charging again in order to prolong battery life as oppose to run time? i usually charge at 30% so 3720mv on my extended battery but i feel maybe i can actually let it drop lower as the ideal charge voltage should be lower?

How to decide time out value according to temperature. How to check Battery open condition, What is Battery open condition normally.

Obviously I made a bit of a typo in my post above. It was of course meant to be 600mA, not 60mA. I’d be grateful for a quick response.

Hi all, I have a phone whose original battery is Lithium-Ion 3.7V 1150mAh. The charger that came with the phone had an output of of 5.25V 60mA. Unfortunately I have lost the original charger but I do have spare charger whose output is 5V 1A. Being a noob when it comes to stuff like this, can somebody tell me if using my spare charger to charge the original battery would reduce the battery’s life in any way? Or would I be better off buying a manufacturer-approved one?

I purchased a flashlight that came with a battery and charger and it said to charge for 8-10 hours before initial use. I put it in the charger and about 12 hours later I remembered it. This is a 18650 battery. I put it in the flashlight and the flashlight didn’t work properly. As I screwed on the end cap the light was bright but as the cap was tightened it seemed to affect the flashlight into not working or working sporadically. I don’t know what to do at this point. looking for advice. Do I need a new battery now? New charger and battery? New flashlight also? I am tempted to return it to the store now, I am sad and wonder if it should have still worked or if I ruined it. ?

Started reading post then saw how many there were so decided to ask my question and comment instead of reading the hole list. Comment- I’d love to see Figure 3 charging to 4.1v instead of 4.2. Question- Although a saturation charge put’s more stress on Li-ion cells at 4.2 providing a little more capacity but shortening life cycles. Does the same thing apply when allowing a saturation charge at 4.1v? Also is there any chargers on the market that will allow you charge to 4.1 or 4.05v then stop charging once the battery voltage has caught up? Indicating saturation charge has started. Or are you just supposed to sit there with your volt meter? A hi voltage alarm would work hooked to the battery. Is there such a thing? Iv only seen low voltage alarms. hmmm. need to do more research.

@peteypablo, I don’t think it really makes any difference if you do 85/35 vs 75/25. Just make sure you giver her enough juice to make it through the day. As for the long term damage, no matter what you do, you’re always doing long term damage. That’s why they will eventually die, no matter what you do. It’s just a matter of trying to do the least damage possible. But as for catastrophic sudden damage, you can run the battery all the way down until the phone shuts off, and it will be fine. The battery itself has a protection chip in it to prevent it from being discharged below a level it could be recharged from. I let mine die all the way sometimes. I carry an extra battery or two in case I need them.

@Mihir, you can use an external, stand alone charger to charge the battery outside of the phone. You can either get one specifically made for your particular battery, or use a universal one. I bought the PPUCLIP by Lenmar. You can get it here: http://www.amazon.com/PPUCLIP-Universal-Charger-Adjustable-Contacts/dp/B001RGYZJS You can just use a voltmeter to see how much voltage there is in the battery. If the PPUCLIP will charge the battery, but you phone won’t, then it’s a bad phone. If the PPUCLIP won’t charge the battery, then it’s a bad battery.

Heys guys awesome information. Im in a problem and i need help. my iPhone 5 is dead due to low battery and didnt start after that. i have taken out my iPhone 5 Li-ion Polymer Battery and i want some way to externally charge it before putting it back on in the iPhone. i basically want to check if its the battery or charging port issue. plz help. thanks.

@vince thanks for the advice. So I assume charging it when it drops below 3.7v is ideal for longevity. I think for coming convenience I’ll charge to 80% and when it drops to less than 3.7v I’ll charge it. I think the problem is if take it off at 3.7v that’s only like 60% which isn’t enough to get metthrough the day. So its a trade off of whether I charge to 85% and charge at 35% or charge to 75% and charge at 25% I don’t really know which is better/worse for the battery stress wise? I guess I have to look at the voltage Ideally on the bottom end how long can I let the voltage go before recharging without it causing long term damage? I notice the voltage is around 3.4v at 30% so maybe I should charge at 40% if I’m at home and not in need of more juice. I use OS monitor app for checking battery temperature and voltage.

On mine, my my voltage would be about 3.7 to 3.6v when my phone would say it was dead. That kind of makes sense, as it was designed for a 1500mAh battery, and I’m using 3800mAh batteries now. The process of totally topping off the battery, then letting it drain all the way down to dead, and recharge it all the way back up again, is supposed to let the phone learn the battery’s capacity, to calibrate the phone to the battery. But it’s never worked for me on my phone. So I gave up trying it, or thinking about it too much, and now I just simply use the dang thing. As far as what’s optimal for the longevity, I mentioned 60/40, but really, if you could hold it at exactly 3.7v, which should be 50%, and charge it any time it drops below 3.7v, and stop charging it as soon as it gets over 3.7v, that would probably be optimal for longevity. Everything else is a tradeoff between optimal longevity and personal convenience. As for the saturation charge kicking in, I don’t really think there’s a certain type of charging that kicks in. I think it’s just that, let’s say your battery is down to 3.3v, and you connect it to a 4.2v charger that can put out 2A, (2000mA). As long as the voltage of the battery is less than the voltage of the charger, the only limiting factor on the current is how fast the charger can put it out. But once the battery reaches the same voltage as the charger, the current starts dropping, not because the charger is doing anything different, but because that’s just all the current the battery can draw. And again, I don’t think there’s a certain percentage where the battery reaches that point, but that it probably depends on how fast you are charging it. So if you’re charging it at only 500mA (standard computer USB), then by the time the battery first reaches the 4.2v saturation stage, it may already be 95% full, but if you charge it more quickly, like at 2000mA, then it might be only 50% full when it reaches the same point. And those aren’t real numbers. I’d imagine that the size of the battery also factors in to it, so what’s considered a fast charging rate for a small battery might be a slow rate for a larger capacity battery. And I don’t really think there’s any way for normal people like us to ever know whether any of this is making a difference or not. If one person’s battery pukes out after two years and another person’s doesn’t, how can we tell if it was because of charging habits vs usage habits, manufacturing differences, climate, etc.

@vince You mentioned that you would reach 1% and knew it was incorrect, at what voltage was it at the time? Im finding that the stock Samsung battery measure in the device ia relatively accurate in that when I use thw oem 2100mah battery and the oem 3000mah extended battery there ia a significant difference in run time between them as in it lasta longer by abou a 1/3rd and takes longer to charge to 80% I just don’t follow rhe article too well and want to know roughly what ia best like I said I charge from 30% to 80% as I assumed that was where satueation charge kicked in but you said I should look at the voltage but what amount wouls you say roughly? Also how low before it’s too low, it could well be I should be chsrging at 40% but I dont know what ia the ideal voltage ro charge to prolong battery life. Ia it the 3.6v and 3.8v like you said?

I uninstalled the app also. I didn’t see any advantage to it, and I know it was wrong, because it would report the same percentage that my phone would report, while I could tell from my voltage that I had a lot more juice left. And indeed, both my phone and the app would say, for example, that I was at 1% (it never says 0%), and it would last another day. So I uninstalled it. I don’t think there really is any optimum voltage at which to stop charging, as it’s just a trade-off. If you could start charging it as soon as it fell to 3.6v, and then stop charging it as soon as it reached 3.8v, that would be great, but how inconvenient! The manufacturers have decided that 4.2v is the optimum tradeoff between longevity, runtime, and convenience. So that’s what the chargers inside the phone, and most other stand-alone chargers, are designed for. Besides, how can you measure it? If you pulled it off the charger at 4.0v, as soon as you pulled it off, it would fall way below that. It probably starts the saturation phase as soon as it reaches 4.2v, but what real capacity it’s at at that point is unknown. If you were very slowly charging it, it might be mostly full. But if you were charging it quickly, then it might not even be half way yet. I think the only way to know for sure, would be to first make sure it really is completely fully topped off, then don’t use it, and time exactly how long it takes to go dead, which would be several days. This would tell you it’s maximum runtime, which would be indicative of the maximum capacity. Then you could quick charge it, and unplug it as soon as it hits 4.19, and see again how long it lasts. The ratio of the two would be how full it was when you unplugged it after fast charging. You could also repeat the test after slow charging, and see the difference. To really top it off, I’d leave it on the charger all night long.

@vince sorry for the late reply I unibstalled the app but from what I remember is if you click below the circle the little icon is clickable and bringa up battery info. ID be curious to know what yours says. I reread this document and im confused still what is the optimum voltage to take the charger off? Im trying to follow what you said about voltage rather than percentage. According to this document what is the voltage when it starts to add saturation charge? And what voltage should I be topping up the charge? At the moment I am doing it at 30% and taking it off at 80% but I need to look at the mv, what is the ideal mv I should start charging at and max mv I should take off for prolonging battery life long term?

Out of curiosity, I just installed the battery doctor app. I’m wondering what it says about mine. Where did you find the stat that tells you maximum power 2100mah?

@vince something you mentioned earlier about that with extended batteries the phone or apps may not recognise the extra capacity and therefore only charge it to the standard original battery capacity. I used battery doctor app to speed charge the extended battery but rrading the stats it says maximum power 2100mah which is incorrect as it’s a 3000mah battery.I did notive it charged quicker but maybe because it’s thibking it’s a 2100mah battery. I I want it to charge properly to 80% would I be better off just letting the Samsung s3 stanfard charge it instead? I cant be sure whether I’m even getting maximum capacity out of the battery or whether it’s only charging as if it’s a 2100mah battery. What do you think would be best?

Thankyou for the primer on lithium ion batteries. I guess I’ll just be charging my devices only partway so i can preserve service life. I’m happy to sacrifice run time in exchange for longer service life. Also, nice tip about turning off the device when charging. I suppose this is why so many GPS batteries have died. i was charging the battery while using it. I used to design battery chargers, and I like this article. It gives me enough to design the charger for this chemistry. There’s also chips from several manufacturers that will do the same.

hmm, strange. I guess I don’t know what to tell you about that. Yes, charging from USB should be slower, and that’s the point, but it should charge cooler, not warmer, so it sounds like something’s wrong.

@vince I find that if I charge via computer USB it overheats when I charge my blackberry with USB charger it charges really slow and overheats the cable and phone feels more. the issue is that 4.3 Android does not let you reduce brightness lower as it was on 4.1.2, im in the lowest brightness setting yet it’s still brighter on 4.3 than lowest setting on 4.1.2. I think that’s the biggest contributer to battery drain, the extra heat etc. im not sure what to do apart from going back down to 4.1.2 which is hassle. even with my extended battery it only lasts slightly more than using a normal 210mah battrry on 4.1.2. Very annoying tbh. Plus on 4.3 it charges slower and heats up quicker

I’ll never get an answer to my questions I sent some weeks ago. I am off and out for good. Thanks for good will anyway, to whoever thinks it may concern them.

I think the best thing you can do, for what you want, is to make sure you always charge it slowly. This probably means not using a wall or car charger, but only charging from a computer’s USB port. USB port standard maximum output is only 500mA, so that will help a lot. Regarding how I use it for GPS without damage, if the current being supplied equals the current being consumed by the device, then the battery really is neither being charged nor discharged. It’s just kind of sitting there idly. The phone will get warm from the screen and all it’s thinking, but the heat is not coming from the battery. Here are a couple apps you might find interesting. I don’t use either of them, so I can’t tell you anything about them, but they look like they’re written for you! https://play.google.com/store/apps/details?ID=com.manor.currentwidget https://play.google.com/store/apps/details?ID=com.ijinshan.kbatterydoctor_en

@vince yeah I agree it be a great science experiment and would help to answer some unaswered questions from doubters and limit the debates whether charging discharging initially improves the battery capacity. also vince as I mentioned before your idea about charging while using gps navigation in the car seems like a goos idea however the extra heat from both charging amd the screen on the whole time would kill the battery surely? Mine reaches 40C! Just having the screen on for an extended period of time at a higher brightness (tho air con I guess would bring it down but im from a cold environment) without even charginghow do you avoid the damage done by the extra heat? I think I’ll either by a satnav instead or juat rely on the extended battery I honestly don’t know how much votage charge my battery is getting but I like to avoid the 2 extremes of 4.2V charging and also below 20% where it puts strain on it.

@vince I think im going to follow your recommendation of looking at the voltage as a guude as oppose to the %. At the moment I charge it around 35% to 80% ie avoiding the saturation charge.however from your previous explanation I realised that % is not a good guide.at what % should I be charging from/to? I’ve noticed that it hangs around 3908mv below 80% which makes me thibk that maybe 77% is probably just as it hits the saturation charge level? What mv should I be looking at as a guide? I still don’t fully understand it but that’s not important

@peteypablo, I like to imagine charge as a thick goo, and a battery as a big shallow pan, which you only fill from one corner, and the voltage is the height of the goo at that corner of the pan. Because the goo is very thick and sticky, when you’re filling the pan, the corner that you’re filling will get full first, but if you wait long enough, all the goo will eventually even out throughout the pan. And when you drain the pan, that corner will drain first, while most of the rest of the pan still has a lot of goo in it. And if you look at the table at the top of this article, you’ll see that the voltage of the battery will reach 4.2v long before the battery is fully charged. The best way to tell how full a battery is from the voltage, is to wait an hour or more after it’s unplugged from the charger. This will give the charge time to saturate throughout the battery, and then when you measure the voltage, you’ll find it’s not as high as you first thought it was. I’ve noticed the same thing happens during discharge. If I’m using the phone for a long time, video, gps, or anything that keeps the screen on, the voltage will eventually read very low. But after I quit using it and wait for a while, the voltage will come back up on its own, even without being plugged in. So voltage can really only be used as a charge indicator after the battery has been sitting idle for a long time. While charging, a better indicator is how much current is flowing into the battery. When you first plug in your phone, the battery will suck up the juice as fast as your charger will provide it, until the voltage of the battery reaches the voltage of the charger, 4.2v. After that, the battery will continue to suck up more charge, but the rate at which it sucks it up will decline as the battery fills up, and will eventually slow to a trickle. There will always be some current due to the inefficiencies of charging, especially if the phone is on while being charged, but even if it is off. So the current will never reach zero, but when the current is close to zero and has stopped decreasing, then the battery is as full as it’s going to get.

@vince I was thinking about what you said about the phone noy recognising the 3000mah eztended battery and only charging a normal 2200mah full. is it possible Samsung would do that? I notice it’s only on. 70% charge and it’s already at 4120mv which seems a bit high? Would I need to get a battery monitor that charges it ptoperly

Hi peteypablo, I’m no expert, so I couldn’t tell you the science behind any of it. But from everything I’ve read, I can’t imagine why going through three discharge/recharge cycles would make any difference. But more importantly, I don’t know how you could even tell if it made a difference unless you timed exactly how long it took to completely die from a full charge each time. I suspect many people might assume the battery is lasting longer because the phone is reporting the capacity dropping more slowly, but the phone is only guessing based on usage. I suspect the three discharge/recharge cycles may be allowing the phone to learn better what the battery’s true capacity is, and thereby reporting it more accurately. I think the only way to know for sure is to make some device that draws a consistent amount of current from the battery, say 100ma, and you time exactly how long it takes the battery to go from 4.2v to 3.2v, then completely charge it back up again, and repeat the test three times. This would be a great experiment for some kid’s science project, don’t you think?

It wont affect the potential of the battery as in ID be missing out? I have a Samsung oem extended battety 3000mah so I assume it’s made as the original 2100 onr it came with. longevity is more important to me so I think I’ll just charge it from 30-80% now ive done thr first 2 charges to 100%.unless there’s a good reason to do a full charge discharge

@vince thanks for the response I see you’re of the train of thought that the initial charge discharge cycle makes no difference but im referring to people who have actually tested out this discharge full chargr cycle for the first 3 charges and actually have results to prove it.do you think it literally is just a calibration thing OR the fact apparently after a few charges it suddenly grts better (I noticed this on my 2100mah Samsung s3 battrry as mentionex the original one, I didnt charge discharge but after the 3rd charge it inexplicably got bettrr. Do you think the reason for the results people have had for lithium ion chsrgr discharge cyclrs initially is just coincidence and it would have happened anyway after 3 charges partially? What I cant figure out is WHY after 3 charges do lithium ion batteries perform better like what is the science behind it? I cannot find the reason on the internet or even a possible theory. I agree with your plugging in the csr charger while using gps in the car but I find that woukd damage the battery even quicker esp in a Samsung s3 as it gets really hot while in use and charging so wouldnt make sense as any extra gains u get from not using the battrry while plugged in is more than cancelled out by the extra heat damaging thr battery. Maybe yours is different. Basically as you are saying that even if I don’t do the initial full charge discharge

Hi petepablo, From everything I’ve read, the idea about fully charging and discharging to get the most out of it is from the old NiCad cells, and is not applicable to Lithium Ion. But old habits die hard and people who don’t know the difference may still recommend wheat they heard in the past, even though it is no longer relevant. I’ve read that LiIon only have so many cycles of life, and so intentionally discharging it like that only shortens its lifespan. In my opinion, the best way to make the battery last the longest is to not use it, or to use it as little as possible. For example, if I’m driving down the road using it for GPS with the screen on, that requires a lot of power, so I have it plugged in during that time. If I use a weak enough power source, it might never charge at that rate. That is, the phone is using energy as fast as the power cord is supplying it, and the amount going to or from the battery is minimal, so I’m not subjecting the battery to any charging cycles. Another thing to do is to not hold the battery at full charge, because apparently that puts a lot of stress on the battery. If you could find an app that limited charging to 75%, then you could leave it plugged in all the time. I don’t know of such an app, but I haven’t looked. Now in answer to another of your questions, it’s very inaccurate to assume remaining charge based on voltage, because the voltage drop during a constant discharge from full the empty is not linear. The voltage drops a lot at first, then almost levels out for most of the cycle, and then drops quickly near the end. So if your device is using the voltage to estimate charge, that might explain why yours quickly goes from 100% to 80% as soon as you unplug it. Because of this, many devices sample the current being used, and use this to count how much energy is used and remaining. Imagine if you know your car can get 400 miles to a tank of gas on average, and you only keep track of how far you drive to estimate how much gas you have left, instead of using your fuel gauge. That’s kind of how my phone works. But because that may change over the life of the battery, some people want to recalibrate their phone from time to time. This is where the complete discharge/charge/discharge procedure comes in. It doesn’t do anything to the battery but wear it out faster, but it helps the phone learn how much use the battery can provide on a full charge, so that it may better estimate the remaining capacity during normal use. It’s hard to tell how the battery’s doing without timing it all the way until the phone dies on its own. Especially using an extended battery. Since my phone doesn’t understand how I can possibly have this much capacity (I use 3800mAh batteries instead of the 1500mAh the phone was designed for), the reading will go down to 1% and still last for another day or more. Now here’s another thing to consider with extended batteries: The hone might pump a full normal battery’s worth of charge into it, and read full, even though the extended battery can actually hold much more. So that’s why many extended battery instructions say to keep it on the charger for a longer time, even after the phone says it’s full. I hope this info is helpful. Enjoy!

@vince I have a couple questions I hope u can answer, I recently bought an extended battery for my Samsung s3 3000mah. Longevity is more important to me than run time (extended battery I don’t need to charge to 100% anymore as it should easily last a day using only 50%) My questions are what are the best way to charge it upon new? It’s a lithium ion battery and I’ve been reading conflicting Комментарии и мнения владельцев and posts with people saying to cycle it for the first 3 times, full charge discharge etc to maximise the capacity of the battery or for it to reach it’s potential. Do you think that is just superficial as in it’s a calibration thing or do you believe it actually might increase/reach the full potential capacity by doing such initial cycles? I thought letting battery charge to 100% and fully discharge would damage the batteries longevity even if only done 3 times? What’s your take on that? Also, if I don’t do the initial charge discharge full cycles would that stop me getting the maximum potential of the battery long term? I’m in 2 minds what to do and thinking to do it just to be on the safe side. So far I used it to 18% then fully charged overnight for over 8 hours (the first charge) thensecond I charged from 38% to 100% (but took it off charge when it said 100% but the light hadn’t turned green) do you think that would impact my battery in any wayfor better or worse? Everywhere I read says it takes a few charge discharges before the battery reaches it’s full capacity. what’s the science behind that? I can’t find a proper explanation I did notice that with my first original 2100mah battery where it got better after 3 charges. Would me not following the procedure have a negative impact on the battery after the 3 initial charges is up? Ie if I don’t do it now it’s too late. I’ve noticed my extended battery drops from 100% to 80% very quickly so seems like it’s not lasting as long I’d hope it or should be doing. Can’t explain. Seems better between 80% to 40% but still unsure, feel like it should be lasting longer than it is.

Any idea what has been removed? I’ve been lurking around here for a couple years now, and don’t recall reading anything before that’s not there now, though that’s not to say I would remember it anyway. I think I’ve learned just about everything I’m going to from this site, but if there was more, I’d be curious to know what it was.

Why has information been removed from this article? There used to be detailed charging information, but it has been removed, why?

Everything You Need to Know About the 18650 Battery

This article tells you everything you need to know about 18650 batteries. We’ll talk about different types, features, charging, lifespans, and our recommendations for batteries and chargers.

  • What is an 18650?
  • Recommended 18650 Batteries
  • Various Battery Sizes
  • Comparing 18650s to Other Common Batteries
  • 18650 Terminology
  • Protected vs Unprotected 18650 Batteries?
  • How much power does an 18650 have?
  • How many times can you recharge an 18650 or other battery?
  • How frequently should I recharge my 18650?
  • How do I know my 18650 is Dying?
  • How can I measure the quality of an 18650 if I am unsure of the age of a battery?
  • 18650 Battery Chemistry
  • What are 18650 batteries used for?
  • What is the best travel 18650 battery?
  • What 18650 Brands are Best?
  • s

What is an 18650?

An 18650 is a lithium ion rechargeable battery. Their proper name is “18650 cell”. The 18650 cell has voltage of 3.7v and has between 1800mAh and 3500mAh (mili-amp-hours).

18650s may have a voltage range between 2.5 volts and 4.2 volts, or a charging voltage of 4.2 volts, but the nominal voltage of a standard 18650 is 3.7 volts.

There are two types; protected and unprotected. We absolutely recommend protected cell 18650 batteries. Protected cells include a protection circuit that stops the cell from being overcharged.

Unprotected cells can be overcharged and burst and potentially cause a fire unless there are specific electronics to protect the battery. The popular LG HG2 and INR and Samsung 25r and 35e are UNPROTECTED batteries, only use them in a device designed to use unprotected 18650s.

We also recommend you stick with high quality brand name 18650s. Knock offs may lie about high mAh (capacity).

The average 18650 battery charge time is about 4 hours. Charge time can vary with amperage and voltage of the charger and the battery type.

Recommended 18650 Batteries

Battery Make and TypeAll are 3.7v Lithium Ion (Li-ion) Max Milliamp hours NotesShop around for best price
Orbtronic 18650 Protected #ORB3500P 3500 mAh Only available direct from vendorgood price
Olight ORB-186C35 Protected #ORB-186C35 3500 mAh Ok price
Nitecore 18650 NL1835RProtected #NL1835R 3500 mAh Good for travel, expensive.Has micro-USB charger port so it can charge itself with a cable/USB port
Panasonic NCR18650BD ButtonProtected#NCR18650-BD 3180mAh Less expensive PROTECTED and good for high drain devices.
Panasonic NCR 18650 3400mAh NOT PROTECTED#NCR18650B-3400 3400 mAh Less expensive but is NOT PROTECTED. Use carefully.
Panasonic NCR18650BE NOT PROTECTED#NCR18650BE-3200 3200 mAh Less expensive but isNOT PROTECTED. Use carefully.

Various Battery Sizes

The following is a picture showing various battery sizes. The 18650 is 1170 cubic mm, the 14500 and AA are 700 cubic mm, the AAA is 467 cubic mm.

Note the 14500’s cannot be used in all AA devices unless they support both 3.7 and 1.5 volt batteries. The 21700 at 1550 cubic mm, is larger than the 18650 battery – the 21700 and 18650 is not interchangeable.

18650 Terminology

A battery might say protected mode 3.7v 18650 3000 mAh low self discharge for high drain devices. What does that all these features mean?

  • “protected mode” means it has an overcharge and overdraw circuit protection built in (more info below).
  • “3.7v” – is the optimal or peak voltage. It will drop as you use the battery.
  • “3000 mAh” measures the amp hours the battery can provide. A higher number is better. The highest realistically available on an 18650 today is about 4000 mAh, anything higher than that is marketing hype.
  • “Low self discharge” is a good thing. That means it will hold a charge in storage. The less it loses in storage the more charge will be left for you to run your flashlight or other device.
  • “for high drain devices” – the battery is optimized for high drain devices. These are devices that use a lot of power very fast, such as RC toy car.

Protected vs Unprotected 18650 Batteries?

Protected 18650 batteries have an electronic circuit. The circuit is embedded in the cell packaging (battery casing) that protects the cell from “over charge”, heat or “over discharge”, over current and short circuit. A 18650 protected battery is safer than an 18650 unprotected battery (less likely to overheat, burst or start on fire).

Unprotected 18650 batteries are cheaper, but we do not recommend their use. Unprotected batteries should only be used where the load/draw and charging is externally monitored and controlled. The protected batteries normally have a “button top”, but check the specifications to make sure. Generally 18650 flat top batteries do not include the protection circuit.

If any 18650 battery is damaged or looks corroded or appears to be leaking, get rid of it at a battery recycling center. Be safe.

How much power does an 18650 have?

A 3.7v a 3400mAh 18650 stores about 2 aH to max of 3.5 aH. It can store about 10 to 13 watt hours. A small air conditioning unit that can cool about 9000 BTU uses about 1100 watts per hour. So it would take more than 110 of the 18650 batteries to run the air conditioner for 1 hour.

In comparison you would need three 12v 40 amp car batteries. But 110 18650s are smaller than three car batteries.

How many times can you recharge an 18650 or other battery?

Recharge cycles vary and are limited. Think of it like a bucket. The trick is that the bucket also gets filled with a tiny bit of other junk over time, so there is less room. As the battery is reused (recharged), the battery degrades due to oxidation and electro-chemical degradation.

This happens to any rechargeable battery such as an 18650, 21700, 26650, 14500, AA, AAA or even a car battery. They can only be recharged a limited number of times.

You want to select rechargeable batteries that can be recharged many times. We specifically recommend 18650’s because they have the ability to be recharged 300 to as many as 2000 times.

How frequently should I recharge my 18650?

The way you recharge your battery impacts the life of the battery. If you can measure it, you want to deplete from 3.7v down it to about 3v before you recharge. If you are not sure, use the device until it indicates a battery needs to be replaced. For a flashlight, run it till the light is dim or goes out.

A good charger will tell you the voltage of the battery so you can eventually get a sense of the life of the battery in various devices. If you recharge too frequently you “use up” the life without a return.

Some people don’t let it dip below 3.3v (or even higher). Each brand and model of 18650 has different maximum cycles. So this is really a process of matching your device and usage to the life cycle of the battery.

Be aware that an 18650 battery that drops below 2.5v may “lock” the device so it can’t be used. The “lock” function happens in devices such as vaping devices.

How do I know my 18650 is Dying?

Here is a list of 7 ways you can tell if you need to get rid of an 18650 (or other rechargeable battery). Look through these to determine if your 18560 is nearing the end of its life and needs to be retired:

  • The battery will lose a charge on the shelf must faster than normal. It loses it’s charge after a couple of days or even worse overnight.
  • The battery gets hot when charging or discharging, warmer than normal.
  • You have used the battery frequently over 2 to 3 years.
  • The battery can hold less than 80% of its original capacity.
  • Recharge time gets abnormally long.
  • If there is ANY cracking or deformation in the battery.
bu-409, charging, lithium-ion, 18650, lithium

These are the 6 signs your 18650 is dead and it is time to get a new one. If you ignore these warning signs you risk fire or even having the battery explode while being recharged.

How can I measure the quality of an 18650 if I am unsure of the age of a battery?

A trick is to buy one or two similar 18650s and mark them “new” with a Sharpe (or label them A, B, C, etc). Then use them and compare their voltage and discharge rates with the questionable 18650s.

Basically you are comparing good vs unknown this way.

You can also gauge temperature this way. Charge both the new and unknown one to see how hot the new one is compared to the one you are unsure of.

18650 Battery Chemistry

There are a number of different chemical combinations for 18650 batteries. We recommend that you FOCUS on protected mode, the chemistry can change and isn’t always reported. Many simply say Li-ION (meaning Lithium Ion).

There are actually a number of Li-Ion batteries. Here are some of the current “types”. Depending on your device type one might be better than the others.

  • LiFePO4 which is Lithium iron phosphate
  • also known as IFR or LFP or Li-phosphate
  • LiMn2O4 which is Lithium manganese oxide
  • also known as IMR or LMO or Li-manganese (high amp draw)
  • LiNiMnCoO2 which is Lithium manganese nickel
  • also known as INR or NMC (high amp draw)
  • LiNiCoAlO2 which is Lithium nickel cobalt aluminum oxide
  • also known as NCA or Li-aluminum
  • LiNiCoO2 which is Lithium nickel cobalt oxide
  • also known as NCO
  • LiCoO2 which is Lithium cobalt oxide
  • also known as ICR LCO Li-cobalt

What are 18650 batteries used for?

Flashlights, electronics, laptops, vaping and even some electric vehicles use 18650s. The Tesla uses 7180 of these batteries. Many high lumen flashlights such as the Thrunite TC15 v3 (best buy) or Fenix PD36 TAC (mo43 durable) use the 18650 or the even larger 21700 flashlights like the Nitecore P20iX a 4000 lumen flashlight.

Laptops and other electronic devices use one or more 18650’s and have recharging electronics built in. 18650’s are also used in vaping (smoking) devices.

18650s are are generally Lithium Ion batteries. If you are familiar with electronics you can change out some battery packs manually, but be careful – using the wrong type of 18650 or using it incorrectly can cause a fire.

Which is the Best 18650 Battery?

Overall best 18650 battery – The Orbtronic 18650 battery. This is an 18650 3.7v 3500mAh Protected cell. This is a high drain battery. We like it but it is expensive.

Best low cost 18650 battery – The Olight ORB-186P26 18650 2600mAh 3. The Panasonic 18650 is an 18650 3.7v 2600mAh Protected cell. This battery is less expensive and slightly lower amp hours than the Orbtronic. Also, this lower cost protected 18650 battery is still more expensive than the unprotected ones.

What is the best travel 18650 battery?

Nitecore NL1834R (currently not available on Amazon but available directly from Nitecore). This is an 18650 3.7v 3400mAh protected cells with a built-in micro-USB charger. It is a few dollars more, but it allows you to charge it on the go and not have to carry a dedicated charger. The unit we have has slightly different packaging.

The cheapest decent one is the Titanium Innovations 18650 at 2600mAh. It won’t last as long as the 3400 mAh Nitecore but is 1/2 the price.

What 18650 Brands are Best?

The Orbtronic, Olight, Samsung, LG, Panasonic, Surefire, ThruNite and Nitecore are good reliable 18650 rechargeable cells. Be sure to buy them from a reputable source such as BatteryJunction or direct from the manufacturer. Note: Amazon stopped selling 18650s.

We don’t use the lower voltage and amperage 18650s, because they have lower amp hours and low peak wattage and lower sustained wattage.

We are willing to pay a few more dollars for the longer life, higher capacity and better quality.

650 Battery Charger

18650 batteries are rechargeable, so you will need a good charger. We use two different 18650 chargers.

The best 18650 battery charger is the Nitecore Ci4 because it can charge pretty much anything.

Specifically, it supports: lithium ion 26650, 22650, 21700, 18650, 17670, 18490, 17500, 18350, 16340 (the 16340 is also known as RCR123), 14500, 10440 and Ni-MH and Ni-Cd AA, AAA, AAAA, C rechargeable batteries. This is our favorite charger for the 18650s.

Our runner up and “best buy” is the XTAR X4 Charger. It is a USB powered 18650 charger. It charges the batteries with any USB power source. This unit is dependent on the power source, and is a bit more expensive.

It has an LCD display for charging status. A 2amp interface yields slower charge speeds. Even the 5amp is slow because it charges at.5 amps. We have used the XTAR and Nitecore with a Nektek solar panel that has a 2amp USB interface and it has consistently worked.

650 Flashlight

The best mid priced 18650 flashlight is the Thrunite TC15 2403 lumen flashlight. It is about 1/2 the price of the PD36 and but a bit less bright. It is a GREAT buy (we have the older TN12 in emergency kits). We suggest two of these instead of one of the Fenix.

It has the following modes: Strobe (975 lumens for 226 minutes), Turbo (975 lumens for 126 minutes), High (652 lumens for 199minutes), Medium (266 lumens for 9.7 hrs), Low (19 lumens/177 hrs) and Firefly(0.29 lumens for 62 days) and it can charge itself with a USB power source. It is waterproof (IPX8) and has a max throw of 223m (764ft).

The toughest 18650 flashlight is the Fenix PD36 TAC. It is not cheap but it is durable and very bright, and has a clip. The light level is 1000 lumens, and it is water resistant to IPX8. This is a “duty” quality flashlight.

The PD36 TAC offers five different brightness levels and strobe:

  • Turbo: 3000 lumen – 1 hr 30 min
  • High: 1000 lumen – 3 hr 15 min
  • Medium: 350 Lumen (8hr 24min)
  • Low 150 lumen – 18 hr 45 min
  • Eco: 30 lumen – 160 hr
  • STROBE (about 3hrs 2000 lumen)

It has a 300 yard or 274 meter throw.

Both the Fenix PD36 or TN15 are great LED Flashlights that use the powerful 18650 battery.

It makes a HUGE difference when you share our articles. Thank you so much!

1 Комментарии и мнения владельцев

August, can you kind of put this in ‘plain English’ for us less tech savvy folks? Are these better than say, nicad batteries? longer life usage wise as well as recharge times wise? Are they more cost effective than other rechargeables? I don’t mind a larger up front cost if it is going to save me more money in the long run. DH uses rechargeable batteries for his work equipment (cheaper stuff, but company reimburses him) and if we can find something more cost effective, that would be great.

Good questions and thank you for the kind words. 1st off I would not switch devices that use AA or AAA to 18650 unless it was an EVERY DAY use. I might use up the old AA or AAA batteries first before considering switching. Remember these are completely different sizes, and weights. But if you have a need for a very bright flashlight or a device that uses the 18650 go for it. They can be recharged and are readily available from dozens of manufacturers and are likely to only get better over time. As an example I would recommend the ThruNite TN12 or Fenix PD35 to a police officer hands down. It has more power so will last longer in use. Nicad (NiCD), Lithium ion, Nickel-Metal Hydride (NiMH),lithium polymer, alkaline and lead/sulfuric acid in a 12volt car battery — are all ways to store energy. Alkaline and straight lithium (like Energizer Ultimate) are NOT rechargeable. We like the non-rechargeable Energizer Ultimate (lithium) over the other alkaline batteries because they are much less likely to leak/corrode. Also the Energizer Ultimate has a 20 year shelf life, so is great for emergencies. Some of the rechargables have longer shelf life too. Again you need to compare the battery to your use. 18650’s are designed for use – not shelf storage. Are these better than say, nicad batteries? longer life usage wise as well as recharge times wise? Not Necessarily, you have to read the specs to confirm. Some of the extreme drain rechargeable batteries will only recharge 100 to 500 times where a more normal high drain could be recharged 2000 times. This matters if you use a device every single day. The AA will last longer for the same amount of light than AAA, and an 18650 will last even longer (see the table). The 18650 has 10x the wattage capacity as the lower end AAA and the 18650 is 3x to 4x the capacity of the AA. Are they more cost effective than other rechargeables? Again unless you have a need stick with AA or AAA rechargeable batteries. The Eneloop AA is a better buy if you don’t have a direct need. It can be recharged 2100 recharge cycles (2100 times). So it would last 4 to 5 years of recharging with every day recharging. Amazon has good rechargeables also, but they are almost the exact same price as the name brand Eneloop. Here is more info on our AA, AAA and chargers- https://commonsensehome.com/best-battery-chargers/ Overall, we recommend any rechargeable including: car batteries, NiMH, NiCD and LiPo. The 18650 is rechargeable Lithium Ion. The only thing we recommend the Alkaline for are gifts or devices that are likely to get lost. Whether you are using AA, AAA, 9v, button or a car battery – match the battery to your needs. But note the Energizer Ultimate has more “capacity” than the normal 14500, but it cannot be recharged. We don’t recommend the alkaline AA/AAA batteries they are cheap. BUT an alkaline battery is way more expensive compared to rechargeable after only 2 to 5 recharges. They can be used in high-drain devices (high lumen LED flashlights, digital cameras etc) BUT their life expectancy will be sharply reduced. They also suffer from more temperature sensitivity. And in day to day experience they tend to corrode and fail more frequently.

Hi August, I enjoy your articles and the great information they contain very much and those of your wife also. I just have one small complaint. Your articles can be shared on social media everywhere for people all over the world but you don’t have a print function. Many times I want to print an article to reference later without trying to remember which website it was on. For everyday living commonsensehome would be one of the first places I would look, but for a certain battery I might have to check seventy different sites and no telling how many articles. Please think about adding the print button.

I totally understand your dilemma and we wanted to provide that feature. Laurie and I researched (and regularly check) for a printing plugin. None of the ones we found so far work on all platforms (Windows, unix, Android, iPhone, Apple mac etc). Here are a couple options: (1) In many browsers you can right click and select print (2) cut the entire post and paste it into your favorite editor and print (3) use the specific browser print function.

Hi August, thank you for putting this article together! I bit the bullet and bought a 2018 Lupine Blika headlamp to use on week long ski trips here in Alaska. Really only use the 3 watt output setting, the larger bulbs give an unnecessary amount of light and drain a battery VERY quickly. The battery pack that came with the head lamp is small and I need more capacity but the larger OEM battery packs are prohibitively expensive. Owner’s manual says the OEM battery packs have 18650 batteries in them so I figured I’d just buy 18650 batteries and make up my own battery packs. Discovered when I went shopping for batteries that there are apparently dozens of 18650 battery types/outputs and I have no idea which one to use. The battery voltage in the owner’s manual says 7.2 volts and it has a visual battery level meter built right into the the battery pack. I’m afraid of 2 things: I assume the OEM battery pack has circuitry to give a consistent power output so the light stays near the same brightness for the duration of the battery discharge cycle. If I make up my own battery pack, I’ll lose that circuitry and may toast my very expensive headlamp due to too high or too low power input. Is there a stand alone voltage, wattage unit I can buy to put in line to properly regulate my home made battery pack output? And, which 18650 battery will be the best for my usage? Because I’m carrying them, low weight and high capacity is necessary. Thank you for any answers you have for my above questions and thank you for putting out this great site! Matt Obermiller

Thanks for the positive feedback. In response to your comment, the output must match the unit you are using. The 1860 I note in the article is protected mode, so it will not burn up or draw outside spec (that is the battery side). The headlamp battery pack may have a voltage regulator built in. The only suggestion I have is to tinker; but only if you can afford frying one. A lot of the LED emitters circuits will take any 18650 – but some may damage the circuit without protection on the LED side OR they may accept any voltage and work fine. The little AA flashlight we reviewed, will use either an AA or 14500 which are dramatically different, so the only way to find out is test it. Watch out for overheating and be prepared to fry your electronics. If you succeed (or fail), would you mind writing a guest post on this? I am sure the community would appreciate the information. Regarding weight, all 18650s are all fairly heavy. I have not seen a LIPO 18650 yet, but they might be available somewhere. If you are going for lightweight the Energizer Ultimate Lithium AA are super light but one-time use. You would need an AA based headlamp such as the Fenix HP15 – and then you could pick AA rechargeables such as Eneloop Pro or Tenergy are both good depending on use profile – in your case I think the higher mAh would be better from the Eneloop Pro. It really depends on what you are doing. If you are out for long periods the solar panel and rechargeable AA or 18650 would potentially cut your load (and allow you to charge a cellphone or any other USB device) but only if you carried more batteries than the weight of the solar panel. The nektek is 1.3lbs though so unless you need to charge a lot of stuff and are out for a long time this probably isnt an option. (ounces are pounds) All the best.

This is the 1st time I’ve ever heard of these and boy am I confused! I’m guessing that you don’t replace your regular rechargeable AA or AAA batteries with these? I’m going to read up and educate myself. This must be something that preppers are into. Love the preppers but the “prepping” is too overwhelming for me being average 65 year old female. Just had to share. I love reading all of the interesting things that preppers are doing. Thanks for letting me share. Debbie

No worries, Debbie. If a device needs an 18650 battery, it’ll be labeled somewhere that it needs one. No swapping out your current batteries required. It’s just a way to cram more power in a relatively small package. Some preppers use them, I’m sure, but they’re mainly for electronic gadgets that suck a lot of power – like our small LED flashlight that’s bright enough to light up the back of the ten acres from the front of the 10 acres.

Hi August. My question is how do I know if my 18650 batteries are not discharging cocorrectly? I bought some Samsung 25R and was notified by the seller not to use them as they were from a bad batch that were not discharging correctly after I had already been using them. They seemed to be working just fine, but I stopped using them anyway. But I have a lot of other 18650 batteris that I use for vaping and would like to know what I need to be on the lookout for. Thanks for your time.

Good question. A bad 18650 can burst or damage the electronics using it. Some electronics have overload protection which greatly reduce the likelihood of damage. Your device may have that protection so the battery is protected once by the in battery “protection” (which might be failing) and again by the device. Regardless, if the manufacturer/seller is recommending not using them, I would stick with that. A burst 18650 is a mess. Get them to give you replacements and move on.

im trying to change dead 18650 batteries in a triple drill battery pack they have the code SE US 18650VT but i cant work out which battery i need, i know they are only 1.5 a/hr…(can i upgrade to bigger) 12v drill the other line under that code is.T C112VSG19R. this is the line i cant interperit or find any info on.thanks for any feedback…cheers

It’s probably safest to contact the tool manufacturer directly. If it’s a battery pack (versus individual batteries), they probably have proprietary battery packs and using anything else is likely to void the warranty.

You’re welcome. Sorry I don’t have more specific info, but there are a LOT of different tools out there, and many companies are bundling the 18650s for specific applications, even solar electric systems. If you’re past your warranty period on the tool, are handy, and the company is no help, you could try swapping out the batteries in the pack with well rated 18650s. I just snagged August and he’s going to comment more on this option.

We cant recommend any tinkering… but we have done it successfully on a laptop and a simple battery pack (both out of warranty). The risk is that you will damage electronics or even start a fire. Many of the devices are built in a way that you cannot easily access the battery packs. Also some are be designed for a specific voltage and/or amperage. The fact that tons of devices use 18650’s in series or parallel make them a tempting self repair project. All we can say is stay safe and if you choose to tinker and are successful, please leave a comment so others will know too. There are YouTube DIY rebuild videos for various brands of battery packs. All the best.

I have seen 18650 battery’s advertised with capacities up to 9900 mAh. Are these real? Is that a maximum a 18650 can be in mAh?

The highest current stable 18650 battery is 3500 mAh. I fully expect the research to improve over time. 9900 is not real. Also watch out for batteries without overcharge protection. Check reviews carefully. Best of luck.

After quick research, I believe it is a different form factor of battery. Not an 18650. The “S1 S2 S3 S4 S5” battery, is a brick design for cellphones, specifically a code that matches the form factor for the specific Samsung model. In my mind those are not 18650’s even if they are described as one. They are square or rectangular and thin and unique to a specific device. They use similar technology to an 18650 and fit inside a cellphone, tablet or other thinner portable computing device.

1s, 2s, is gow many cells in series. series connection will increase voltage, parallel will increase capacity. 1s would be 1 cell @3.7v 2s would be 2 cells connected positive to negative (think old flashlight stacking batteries in handle) @ 7.4, 3 s being 3 cell- @ 12.1v and so forth.

hello, I am a dentist and use my led surgical light powered by battery pack of two pack 18650 2200mah, I just replaced my battery pack with a fresh battery pack. question: how can I make my battery pack last longer? use it till it drains and then recharge? or keep it connected to my charger intermittently through out the day as I use is daily. thanks Drlopez

Good question. We added a couple sections in the post to answer this. A quick answer is you want to balance recharges with “using up” the battery. Check your specific battery specifications for lifecycle and charging recommendations. In general though, if you recharge before the battery is at least partly depleted you “lose” a recharge – and batteries only have 300 to 2000 total recharges before they should be replaced. Generally you want the battery to drop from 3.7v to about 3v. In other words don’t top off a 3400mAh battery at 3300mAh instead charge it at 2500mAh or even 2000 (where you choose depends on the number of recharges you expect and the devices sensitivity to low voltage/amperage). I hope this helps.

Hi August. I do not agree with you regarding the charging of batteries. If you look at the datasheets of these batteries, you will see that the lesser the drain on the battery the longer the battery will last. It is the same with cellphone batteries, also Li-ion. My cellphone battery get charged every night. Mostly my battery still have 35% to 45% charge left. I have no problem getting 2-3 years life out of my cellphone battery. Years ago people was told to fully discharge the battery before charging. That might have been correct for old battery types like Nickel Metal Hydrate batteries, but Li-Ion batteries give you the best life performance if you can keep them between 40% to 80% charge. I viewed the datasheet of a 100Ah Li-FePo4 battery pack, used for solar systems, the other day. It is rated at 2000 charge cycles, but they gave a graph showing expected life time at different discharge depths between charges. If you don’t discharge it more than 50% you can get almost 20 years life out of the battery, based on every day recharging via solar.

You are correct. It is why I like larger packs where possible (higher wattage at same voltage to allow lower overall drain). And as you noted, this is recommended by the manufacturers and has to do with the design of the 18650 batteries. I don’t follow all the rules, I leave mine in flashlights and other devices until they don’t light up the way I want. So I am not staying in the 40% to 80% range. I don’t worry about the cycle rates because 2000 is awesome but 500 to 1000 is just great too and I don’t have to monitor them all in detail, but if you do you can drastically extend their life. Thanks for the feedback.

I’m trying to use 18650 in a trail camera as directed by the owners manual. The 18650 I bought are Nurie18650-1A. 3.6 v. 2600mAh, it call for 2 batteries in the camera. How do I know if these are the correct battery ? It mentions something about PR200 when discussing the battery ?

I believe you are asking about the PR200 Trail Camera – it looks like that model requires any two 18650s. Although the Nuon NURE18650 will work, it lists that it is a high self discharge battery (it loses charge just sitting around). Also, the Nuon is only 2600mAh. Instead I recommend a 3000mAh to 3400mAh protected mode low self discharge 18650, such as the: Samsung, Panasonic, Orbtronic, LG or Nitecore. Finally, you need to confirm with the camera manufacturer manual for exact information and battery types.

Hi. What a useful website! I am in the process of changing the Samsung 1500mAh18650 batteries on my AEG vacuum cleaner. it is 5 1/2 years old and they have gone already! (joke). Am I best to replace with the 18650 3500mAh units. Same physical size etc. Also, the manufacturer’s instructions are to leave the cleaner permanently on charge. Is that a good idea? Thanks

High mAh will in general be safe- it will just run longer (more capacity) – the wattage is 3.7v x 1500 = 5500m-watts vs the 3.7v x 3500 = 12,950 m-watts. The “charge all the time” part is more tricky. It depends on the device, electronics and charger. If you get lower self discharge batteries i suspect you would only want to charge it before use (or after its dead). You really need to confirm with the manufacturer to confirm – if they have another small battery in the electronics the trickle charge could be to keep the unit powered. I cant be sure, so use your best judgement.

Hi August, I am one of those species that are naturally inquisitive and will forever “tinker” with everything. the latest being replacing my NiCD batteries in my cordless drill with LI-ion batteries. I have matched the voltage and the drill 18V works fine. I have not yet recharged the batteries.,Can I use my NiCD charger to charge the replaced LI-ion batteries? A friend of mine bought me Rekieta 18650 12000ma/h3.7v batteries from a china shop which I have tried in a similar way on my 14.4v drill, also matching the voltage. Sadly the drill does not work although the voltage is correct. the lettering on these batteries are very foreign and I cannot determine whether they are indeed rechargeable or not. HELP.

August is up to his eyeballs in alligators at work at the moment, so not much time for the site. From what I was able to find online at this QA on Quora “Can I use a NiCad battery charger for lithium?“, the most likely answer seems to be “No. voltage profile, current profile, and current tapering profile are all different.” Batteries can explode or have a meltdown under conditions that they were not designed for, so be careful.

I just received a flashlight that uses a 18650 battery. The flashlight says “shustar”, “Albinaly”, and “CE RoHS” in different places. The battery says “shustar”. The wall charger has a light on the plug-in part that glows yellow when plugged in; don’t know if it changes color when the battery is fully charged because I just started charging the battery. Did I get anything worthwhile? I assume the battery is not a protected type.

The best I can say is track back the manufacturer and try to find the specifications and documentation. I do not know which make/model devices you are using. We recommend the better reviewed, name brand flashlights and chargers. The name brand are a few more dollars but you can call for support and they have wider reviews. Regarding the battery, we recommend that you use a protected mode 18650 regardless of the device unless it specifies an unprotected 18650.

Hello. I have a question that I think will be more common this year with the popularity of outdoor Wi-Fi security cameras, and the solar charging panels to keep the cameras running day night. I have purchased a few of the solar chargers dedicated for Amazon Blink cameras. The Blink cameras run on a pair AA Li-Ion internal batteries, that are advertised to “run for up to two years”. Obviously, replacing the internal pair of AA batteries with a pair of 18650 rechargeable batteries, running from inside a solar panel, to the USB port on the cameras, should do better. The Blink cameras’ Chinese aftermarket dedicated solar panels have two 18650 flat top 3.6V 2600 mAh of various branded batteries mounted in the back of the panels; where there is also a bit of circuitry on a small board. The solar panel specs says it outputs 6.0 V, 0.4 A. I am curious about what type of 18650 batteries will work best in this variable load/trickle charge situation. The cameras are awake full time 24/7, but not recording and/or sending Wi-Fi radio signals much of that time. The battery usage is a situation where there is a tiny draw full time, and larger draw occasionally when they are motion tripped, and also being recharged maybe 12 – 14 hours a day at various levels of solar power. Most of what I’ve seen for the small solar power panels are using lower capacity batteries (2,200 to 2,600 mAh). Aside from price, is that because the charging current from the solar panel is so low (Max 0.4A)? I’m concerned about the the “flat top” battery style (not protected?), supplied in the panels, but I used those for years in E-Vape service. Just lucky? I think the high end chargers used, along with the vape devices’ circuitry maybe provided protection? Well that’s just one concern. The bigger question is what style/type of 18650 will work best (most durable) for the daily variable solar charging, along with simultaneous variable draw from the batteries. I see a plethora of brands, and models out there, and don’t relish frequently changing out batteries whilst balancing on a ladder. Like some other commentators, price has a lower priority/concern than ladder climbing frequency.

The solar panel USB feed is a good idea. To confirm runtime etc I would need specs on the panel. Two 18650s provide up to 25ah where the two AA provide 9ah. So the panels (if they charge even with lower quality batteries should do far better than the internal AAs and last for years. Solar Panel. The wattage (output) of the solar panel and amount of sun it gets is key. If the panel can’t get enough sun the batteries will eventually die. Solar Panel 18650. Nearly all manufacturers use the cheapest battery that will perform in the device. Unprotected are cheaper so they build the “protection” into the electronics instead of the battery. If you replace the unprotected battery with a better protected battery it will likely give you better life but I cannot be sure. If the panel gets enough sun it is probably unnecessary to replace the batteries right away. One way to confirm them is remove them and put them in a protected charger to check their max wattage. Alternate solution. The 6 MinPak waterproof 6×18650 pack could use your old vaping batteries and still have more than 10x the watt hours. If it works, you could just change them out every 3 to 5 years, recharge and replace. This might be a better pick for wooded areas. As I don’t have specs, any “creative solutions” would need to be tested.

bu-409, charging, lithium-ion, 18650, lithium

Hello August: I have a cordless vacuum (Type AE – 14.4V DC) hat uses 4 batteries LGDAHB31865. I searched and find that this refers to a 18650 BATTERY. I want to replace it for equal or ideally better ones. I live in Canada and I do not find the reference above mentioned anywhere other than China. Could you please help me with some brand name, reference o place where I could buy it. I’m older and the vacuum is like new and been working well for me (light and handy), but the batteries are almost dead after 2 years and the manufacturer offers no help even know it is a big Company. Thanks in advance Jaime R.

Yes the LGDAHB31865 is a High Discharge LG 18650. They appear to be available on eBay. I can’t suggest using any other battery. The risk is that the electronics might be tweaked to match that specific battery (charge/draw). First, idea is to charge the LGDAHB31865 batteries outside the unit to see if they truly are dead (if they dont charge then you know its not your unit). Second idea… I suspect you could use two 2 packs Orbtronic 18650 batteries (I have these). There is a risk that this could damage the vacuum or the new batteries. I suspect the Orbtronic might allow the unit to run longer also. Although I cannot recommend it, if you test it out please keep us posted. Best of Luck Jaime R, sorry I could not provide a definitive answer.

August, thank you for your prompt answer. I’ll check on eBay to see if they have it. The solution of the Orbtronic 18650 batteries, will be more expensive than buying a new vacuum. Nowadays, it is difficult to find and appliance that last more than 2 years.

Yup that is why they use cheap batteries, everything is about cutting unit costs. BatteryJunction.com might have cheaper one unprotected 18650s (which I suspect that your vacuum is using). We buy the expensive batteries and they last much longer. Again be careful, the electronics could smoke if they had a tight match to the battery specs (and remember unprotected 18650s can burst).

August, this is the type of batteries that this machine uses (http://www.cylxpower.com/previewimg.jsp?fileID=ABUIABACGAAgseS5xQUo7rLI8wYw6Ac46Ac); I guess they are unprotected. I did find on eBay from a Canadian seller this (https://www.ebay.ca/itm/2X-18650-9900mAh-Li-ion-Battery-3-7V-Rechargeable-Canadian-seller/333462620310). Do you think that will work? Thanks again for all your help.

Hi Jaime. August is having an extra crazy week at work (they dumped a big project that would normally take months in his lap and want it done this week), so I decided to chime in. For better or worse, the only way to know for sure it to try and see if it works. The odds look good, but you can’t tell for sure until you try.

Please let me be BLUNT! There is no such thing as an 18650 Cell that can deliver over 4000 MAH! NONE Any advert saying that their battery provides this is a Lie False Adverts! and from testing they are usually less than 2400 Mah. Additionally they have a high “internal” resistance, which means that there is a higher voltage drop at higher current levels. My personal guide line would be : Buy Japan or South Korea mfg 18650’s ALL China branded are inferior and/or falsely labeled. Many of the Adverts are just LIES! Amazon and Ebay should stop listing them.

Hi, I just recently started buying LED flashlights powered by 18650’s. I understand the higher mAh batteries give longer runtime, but now I just ordered a “high power” flashlight that says to use “high discharge” rate batteries of 10A or more, so my question is, can you tell if a 18650 cell is “high discharge” just from the numbers/ letters printed on the side of the battery? Thanks, Ed

Some battery types are designed for high discharge, some are “LSD” low self discharge. The high discharge ones generally don’t hold a charge in storage, but do a good job of providing power fast. The low self discharge ones don’t provide power fast but also don’t “leak” power over time. If you have an 18650 battery you will need to research the type of battery to find out if it is normal, low self discharge or high discharge.

Ok, August, so if I understand you correctly, most high discharge batteries will say on the casing “High discharge” or similar- These are the batteries I got; https://edisonbright.myshopify.com/collections/batteries/products/3-pack-edisonbright-ebr34-3400mah-18650-rechargeable-li-ion-protected-batteries. and I am ordering this flashlight; https://lumintoplighting.com/lumintop-gt-mini-pro-3500-lumens-xhp502-led-high-intensity-outdoor-flashlight-p0068.html. which is 3500 lumens- I don’t want to smoke the battery…. Seem like they might work? Thanks, Ed

Ed, It would be best to check with the people selling that specific flashlight. We haven’t used that particular product before, and they should know the items they’re selling.

There are far too many general statements here. The author states his opinion of the best batteries and flashlights. Some of my flashlights are definitely better to use unprotected cells for the same reason some of my vape devices do. The protection circuits are sometimes built into the lights now, and protected batteries will not allow the amp draw needed because they are capped at 10 to 12 amps. Also the best light is often based on the intended use…do you need a long throw, more flood, or combination. Some lights now even have proprietary batteries and chargers. That is the case with Olight Seeker 2, but you can actually use an externally charged 21700 orbtronics protected battery with the buttontop closest to the cap. You can’t however charge that battery in the light. The Olight special modified battery re-routs a negative contact to the positive side for the magnetic charging. The negative terminal on the light is at the head.

Hi August, Is it safe for 18650 batteries to be “plugged in” all the time, for example in applications like emergency back up lights, where they come on only during power outages? Regards, Paul

August is up to his eyeballs at work, so I’ll chime in. While it might not be ideal from a battery life perspective, if that’s what the device requires to function, that’s what it requires to function. It should not be safety concern (no risk of explosion, etc).

I’m buying a protected 18650 battery for a solar charging light in my garage. I only need one, but the SH is the same as the price of one battery. If I order 2 or 3 and don’t need them for 2-4 years, will they still be good or am I better off just buying the one now and deal with it.

After doing some digging, it looks like most people are not having any issues with 18650 batteries that have been stored a few years. The article “Proper 18650 Battery Storage” suggests a charge of roughly 40% for best storage life.

HB-X2 Battery Charger / Powerbank

Keep your adventure charged up with the high capacity HB-X2 battery charger power bank.

The HB-X2 is a compact three-in-one charger, storage, and powerbank solution for 18650 batteries used in the Huni Badger. Connect the HB-X2 to a USB power source (2A minimum recommended for faster charging time) with the included USB-A to USB-C cable, and insert up to 2 batteries in the dual slots to charge. It supports pass-through charging, which allows for charging a connected device while charging the batteries. Using the magnetic cover converts HB-X2 into a convenient battery storage/powerbank. The HB-X2 is designed with a USB-A output which can provide power to charge your portable devices. The 4 LED indicators display battery level and charging status.

After fully charging the HB-X2 and its time to go mobile, you can be prepared for those times when you need some extra juice!

Features and Specs:

  • Small and compact portable design
  • Dual slot for charging 18650 rechargeable batteries
  • Reverse polarity protection
  • 5V USB input to charge (2A minimum recommended)
  • Overcharge protection, auto cut-off when charging complete
  • One USB-A output for charging portable devices
  • Output over-current and output short circuit protections
  • 4 LED battery level and charging status indicator
  • Input: DC 5V (2A minimum recommended for fast charging)
  • Charging current 2A one battery or 1A each if two batteries installed
  • USB pass-through function during charging to conserve battery life

Package Includes:

1 x HB-X2 dual slot 18650 Charger and Powerbank

1 x USB to Micro USB cable

FOR USE WITH RECHARGEABLE BATTERIES ONLY. Other types of batteries may cause personal injury. Do NOT leave batteries charging unattended/overnight!

NOTE: Use special caution when working with Li-ion cells, they are very sensitive to charging characteristics and may explode or burn if mishandled. Make sure the user has enough knowledge of rechargeable batteries in charging, discharging and assembly before use. Do not use if charger or battery wrap is damaged in any way. Always charge in/on a fire-proof surface. Never leave charging batteries unattended. We are not responsible for damage if there is any modification of the batteries/chargers in any form or shape. We are not responsible for any damage caused by misuse or mishandling of batteries and chargers. We only recommend using Lithium Ion rechargeable batteries with a control circuit (protection PCB) to assure safe charge, discharge, etc, use of lithium ion batteries with a protection circuit is potentially hazardous


Huni Badger will not be held responsible or liable for any injury, damage, or defect, permanent or temporary that may be caused by the use of a rechargeable battery. Please have a full understanding of the batteries you are using, how to care for them properly, and how to use them safely.

How to Pick the Best 18650 Battery and 18650 Battery Charger

Lithium-ion 18650 batteries are a very popular choice for high-power devices that also require long-lasting batteries in terms of capacity, low self-discharge rate, and a large number of charging and discharging cycles.

18650 rechargeable batteries come in countless versions, with many features, some of the most important being capacity, maximum pulse and continuous drain current, charging current, protective electronics, etc.

Updated: November 12, 2021.

650 Battery Dimensions

As its name suggests, 18650 battery dimensions are (diameter x length) 18 × 65 mm (0.70866 x 2.5590 inches).

Actual dimensions slightly differ from manufacturer to manufacturer, but these small variations in size usually make no problems.

Before buying new 18650 batteries, there are few things to consider.

650 Battery Features and Specifications

Capacity and maximum discharge current. these two values are closely related since high capacity design limits maximum safe discharge rate and vice versa, high discharge current design limits the capacity of lithium batteries.

For example, high-capacity 18650 batteries have capacities up to and even more than 5000 mAh, but the maximum safe continuous discharge rate of such batteries is often in the 3-10 Amps range. high-capacity 18650 batteries.

On the other hand, 18650 batteries that are able to provide continuously 20-30 Amps and up to 40-50 Amps for 1-5 seconds safely, usually have a capacity in the 2500-3000 mAh range. high-drain 18650 batteries.

Note: when promoting their batteries, some manufacturers tend to overestimate the characteristics of their batteries. Thus, it is very important to read reviews and recommendations of other users as well, not just specifications and features provided by manufacturers. Or go for reputable brands and perhaps pay slightly more.

Flat or button positive (top) side. there are two versions of positive (top) side: flat top and button top.

Most of the devices support the use of both types, but just to be sure check the documentation of your device or go for the type that is already working well with your devices. better safe than sorry.

Soldering tabs or not. if you have issues with the 18650 battery pack, replace all the batteries with the new ones that have the capacity and charging/discharging currents in the same range (or better) as old batteries.

Always use the same batteries from the same manufacturer, preferably from the same batch and if you have to solder their tabs, let the professionals solder them for you since it can be a very tricky task to do. Or go for an OEM replacement battery pack, which can cost more, but it is a safer option if you are not absolutely sure what are you doing!

Protected 18650 batteries. since lithium-ion batteries are sensitive to charging and discharging conditions, their temperature, and other parameters, some 18650 models come with built-in protective electronics, which monitor the parameters of the battery and if required, protect the battery by shutting it off until conditions are changed.

Protective electronics require some space and thus slightly decrease the capacity of the batteries. IMHO, more than a worth feature, unless your device already has some sort of battery monitoring function.

Unprotected 18650 batteries feature a somewhat larger capacity, but their condition must be monitored by the external device.

Rewrapped batteries. some manufacturers buy cheap 18650 batteries, wrap them as their own and sell on the market, sometimes with highly exaggerated claims regarding their capacity and currents. On the other hand, reputable sellers like Panasonic, Samsung, LG, Sony, etc. thoroughly test their batteries and discard the bad ones. Of course, batteries from such brands cost more, but in the long run, their batteries are actually cheaper.

The following table lists few high quality 18650 batteries with their most common features:

Model Capacity Max. Continuous Current Comment
LG HD2 2000 mAh 30 A Strong, decent capacity
LG HE4 2500 mAh 20 A Nicely balanced battery
LG HB6 1500 mAh 30 A Very powerful battery
LG HG2 3000 mAh 20 A Strong and good capacity
Panasonic NCR18650B 3400 mAh 6.8 A (12 A, 5 sec) For low current devices
Samsung 25R 2500 mAh 20 A (30 A) GOLDEN STANDARD 🙂
Samsung 30Q 3000 mAh 15 A Can go up to 20A, but.
Sony VTC4 2100 mAh 30 A Strong, decent capacity
Sony VTC5 2600 mAh 20 A Nicely balanced battery

Note: Amazon affiliate links in the table open in the new Windows, feel free to check them.

Samsung INR18650-25R 18650 2500mAh Battery

Samsung INR18650-25R 18650 2500mAh or for short Samsung 25R is the golden standard regarding high power 18650 batteries. It has a high maximum continuous current of 20 Amps and many people have pushed it to its limits draining it with 30-40 or even more Amps (obviously, not recommended).

Its capacity of 2500 mAh at first looks modest, but if you take the higher capacity battery and drain it with 15-30 Amps, the actual capacity will be decreased, just like the number of charging and discharging cycles.

For low current devices, Panasonic NCR18650B features 3400 mAh capacity and it is able to provide almost 7 Amps (6.8 Amps, to be correct) safely.

Over time, manufacturers improve their designs and new batteries come with larger capacities and larger supported drain currents, but these batteries in the list have been tested in real-life applications countless times.

IMR, INR, IFR, or ICR 18650 Batteries

Labels of 18650 batteries often include abbreviations like IMR, INR, IFR, or ICR. These abbreviations describe actual battery chemistry:

Note: there are other chemistries on the market too, including hybrid technologies like Lithium Nickel Cobalt Oxide (LiNiCoO2), Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2), etc.

650 Battery Chargers

Modern 18650 battery chargers are intelligent battery chargers that can sense the battery type, chemistry, condition, etc.

Often these battery chargers can be used for charging a broad range of batteries, including NiCd, NiMH, and various lithium rechargeable batteries.

The most important features of intelligent battery chargers include:

When choosing a battery charger for your needs, pick a battery charger according to your current, but also future needs, too.

650 Batteries With USB Built-in Charger

To simplify the charging of 18650 batteries, some models feature a built-in USB battery charger. when charging is required, the battery is simply connected to a USB port, and onboard electronics monitor battery parameters and do all the work.

These models are highly recommended for people needing just a few 18650 batteries for their devices.

Although built-in USB battery chargers require some space and thus decrease the battery capacity, they also often monitor battery condition during operation and protect it, if required.

650 Battery Equivalents

When replacing the 18650 battery, the best option is to use another 18650 battery with the same, preferably better characteristics.

However, some devices allow the use of other batteries, like 3xAAA batteries, 2xCR123A batteries, and similar.

Also, the CR123A battery is available as a non-rechargeable lithium battery providing 3.0 V and as a rechargeable lithium-ion battery (often designated 17340, 17345, or 16340 battery) providing 3.6. 3.7 V.

This difference in voltage (3.6 vs 6 vs 7.2 volts) can damage many devices and one must check the documentation of a particular device to be absolutely sure if 2xCR123A batteries are supported.

Note: non-rechargeable lithium CR123A batteries from reputable brands have a shelf-life of often 10 or even more years and even after 10 years, they can provide large currents easily. Thus, CR123A batteries are often recommended for standby devices like EDC flashlights, panic lights, and similar devices that are often not used for years, but when they are used, they must operate reliably.

For devices that are often used, a rechargeable 18650 battery is recommended choice. But for standby applications, 3 high-quality AAA batteries (alkaline batteries, not rechargeable NiCd or NiMH batteries) are a more reliable choice.

Even if you have rechargeable NiCd or NiMH AAA batteries, do yourself a favor and get one good 18650 battery with a built-in USB charger. such a battery will easily outperform 3xAAA batteries and it can withstand more charging/discharging cycles.

650 Battery Flashlights

18650 batteries are commonly used as high-power and high-density energy sources for LED flashlights, ranging from compact EDC flashlights to strong and powerful tactical flashlights.

18650 flashlights usually feature one to two 18650 batteries, rarely more. only high-output, very bright flashlights feature three, four, or even more 18650 batteries.

Since LED flashlights use a built-in LED electronic management system, some 18650 LED flashlights allow the users to use either 18650 batteries, CR123A batteries, or AA batteries.

As said before, two CR123A batteries may replace a single 18650 battery, which is recommended for EDC flashlights that are rarely used but must operate reliably even after years of storage.

In order to provide the highest possible IPX waterproof and dustproof rating, some 18650 LED flashlights use various USB magnetic charging cables, allowing the batteries to be recharged without any openings on the battery’s body.

Amazon Search:

Note: Amazon link opens in the new window, feel free to check it for the most up-to-date offers and prices.

650 Battery vs 26650 Battery

18650 and 26650 batteries share the same length, but the 26650 battery is wider and has some ~2x larger volume.

Thus 26650 batteries are often used in devices requiring even more power and energy. 18650 battery packs plenty of energy, but 26650 packs on average 2x more.

18650 battery can be used instead of 26650 battery using a special battery holder, just be sure that 18650 battery can provide enough current for that particular device.

IMHO, 18650 batteries are great, but if your device supports the use of 26650 batteries, go for 26650 batteries.

650 Battery Frequently Asked Questions. 18650 Battery FAQ

Here are some of the most common questions about 18650 batteries:

How to charge a 18650 battery?

Depending on the 18650 battery type, the best way to charge the 18650 battery is to use a 18650 lithium-ion battery charger.

18650 batteries that feature micro-USB or similar charging ports may be used via USB charging ports found on computers, laptops, or using USB wall chargers.

How long do 18650 batteries last?

18650 battery may last up to 300-500 charging cycles. after which its capacity drops down or below 80% of the nominal capacity.

How long does it take to charge a 18650 battery?

Charging time depends on the battery capacity and charging current, but it shouldn’t be too fast. charging times around 3-5 hours are considered optimal, although there are models that can be charged with much stronger currents.

18650 battery storage best practices?

18650 battery should be stored at room temperature (68-77°F, 20-25°C) in a dry, non-condensing area. Also, the lithium-ion batteries should be stored and transported in a semi-charged state (50-60% of nominal charge).

18650 battery should not be carried in the or bag with metal items (keys, for example) present which may short-circuit the battery.

What is the voltage of a completely charged 18650 battery?

End charging voltage depends on the exact battery chemistry and ranges from 3.6 to 4.2 volts.

Is a 18650 battery the same as AA?

No, the 18650 battery is a lithium rechargeable cylindrical battery featuring physical dimensions of 18.6 × 65.2 mm, while the AA batteries feature physical dimensions of 14.5 x 50.5 mm and are available in various both non-rechargeable and rechargeable chemistries.

Some devices intended for 18650 batteries also come with a special battery holder that allows them to use either 18650 or AA batteries, but due to the larger dimensions, 18650 batteries are able to store more energy than AA batteries.

Which is better, a single 18650 battery or 3x AAA batteries?

AAA batteries feature physical dimensions of 10.5 x 44.5 mm, while 18650 batteries feature physical dimensions of 18.6 x 65.2 mm.

Some devices intended for 18650 batteries come with special battery holders allowing them to use either 18650 batteries or 3x AAA batteries instead of a single 18650 battery.

Although such battery holders allow the user to use whatever battery is available, a single 18650 battery is able to store more energy than three AAA batteries.

Is there any reason you shouldn’t or can’t make a vehicle battery out of several lithium 18650 batteries?

While 18650 batteries may be used for making large battery packs, each of these 18650 batteries must have a separate wire for monitoring the battery’s condition and for equalizing the battery.

Since such battery packs require a huge number of individual 18650 battery cells, such battery packs would also require a rather complex Battery Management System (BMS).

For example, in order to create a 12V 100Ah battery pack using 3.2V 3000 mAh 18650 Lithium Iron Phosphate (LiFePO4) batteries, one would need 136 (4S34P) 18650 batteries, and only 4 (four) 3.2V 100Ah Lithium Iron Phosphate (LiFePO4) battery cells.

It is much easier and less complex to connect 4 cells in series than 136 batteries in 4S34P configuration.

And electric vehicles use much larger battery packs than simple 12V 100Ah batteries.

For short: the best battery replacement for a 18650 battery is another 18650 battery. plain and simple. When choosing new batteries, consider your old batteries and the device(s) you have, and their requirements.

Note: never, but really never charge lithium batteries with chargers not designed for such batteries. Also, never throw them in fire, leave them in the hot car, or similar. And, after they served you well, dispose of them properly (they can be almost 100% recycled!).

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