Battery chargers. Aa battery charger batteries

Battery chargers

by Chris Woodford. Last updated: February 11, 2023.

P ower to go—aren’t batteries brilliant? The trouble is, they store only a fixed amount of electric charge before running flat, usually at the most inconvenient of times. If you use rechargeable batteries, that’s less of a problem: click your batteries in the charger, plug in, and in a few hours they’re as good as new and ready to use again. A typical rechargeable battery can be charged up hundreds of times, may last you anything from three or four years to a decade or more, and will probably save you hundreds of dollars in buying disposables (so it’s brilliant for the environment too). But exactly how well your batteries perform depends on how you use them and how carefully you charge them. That’s why a decent battery charger is as important as the batteries you put into it. What is a battery charger and how does it work? Let’s take a closer look!

Photo: Solar-powered battery chargers, like this one made by BEAM, are sure to become increasingly common as more of us switch to electric cars. The overhead canopy contains a 4.3kW, photovoltaic, sun-tracking solar panel and feeds onboard batteries so it even works at night. It can charge up to six electric vehicles at a time. Photo by Erin Rohn courtesy of US Marine Corps and DVIDS.

What are batteries and how do they work?

If you’ve read our main article on batteries, you’ll know all about these portable power plants. An example of what scientists refer to as electrochemistry. they use the power of chemistry to release stored electricity very gradually.

What happens inside a typical battery—like the one in a flashlight? When you click the power switch, you’re giving the green light to chemical reactions inside the battery. As the current starts flowing, the cells (power-generating compartments) inside the battery begin to transform themselves in startling but entirely invisible ways. The chemicals from which their components are made begin to rearrange themselves. Inside each cell, chemical reactions take place involving the two electrical terminals (or electrodes ) and a chemical known as the electrolyte that separate them. These chemical reactions cause electrons (the tiny particles inside atoms that carry electricity) to pump around the circuit the battery is connected to, providing power to the flashlight. But the cells inside a battery contain only limited supplies of chemicals so the reactions cannot continue indefinitely. Once the chemicals are depleted, the reactions stop, the electrons cease flowing through the outer circuit, the battery is effectively flat—and your lamp goes out.

Photo: Ordinary batteries (like this everyday zinc-carbon battery) are only designed to be used once—so don’t attempt to recharge them. If you don’t like zinc carbon batteries, don’t start trying to recharge them: buy rechargeable ones to begin with.

That’s the bad news. The good news is that if you’re using a rechargeable battery, you can make the chemical reactions run in reverse using a battery charger. Charging up a battery is the exact opposite of discharging it: where discharging gives out energy, charging takes energy in and stores it by resetting the battery chemicals to how they were originally. In theory, you can charge and discharge a rechargeable battery any number of times; in practice, even rechargeable batteries degrade over time and there eventually comes a point where they’re no longer willing to store charge. At that point, you have to recycle them or throw them away.

How battery chargers work

All battery chargers have one thing in common: they work by feeding a DC electric current through batteries for a period of time in the hope that the cells inside will hold on to some of the energy passing through them. That’s roughly where the similarity between chargers begins and ends!

Charging methods

There are, broadly speaking, two different ways to charge a battery: quickly or slowly. Fast charging essentially means using a higher charging current for a shorter time, whereas slow charging uses a lower current for longer. That doesn’t mean the charging process is just a simple matter of passing a steady current through the battery until it’s charged. They are several common methods of charging (plus a few more we won’t go into here). [1]

Photo: Battery chargers look simple, but they’re surprisingly complex inside. Different types of rechargeable batteries need charging in different ways, for different times, sometimes using several different methods in turn, which make up what’s called the charging algorithm. A charger like this is constantly sensing what the batteries inside it are doing and adjusting the charging process accordingly.

Pulse charging involves sending intermittent pulses of high current through the battery, with rest periods in between to allow the battery chemicals to absorb the charge. In crude terms, the pulses are a little bit like the thumping charges to the chest you see an emergency responder giving to someone who’s suffered a cardiac arrest, except that they continue until the battery’s voltage climbs toward its rated, peak value and the battery is fully charged. (Pulse charging can also be useful for reviving older, degraded batteries, such as lead-acid or nickel-cadmium, in which crystals have grown and impeded the batteries’ ability to keep on working; the pulses of electricity break the crystals down so the battery works normally again.)

In taper-current charging. the charger starts off using a high, constant current, which progressively lowers to a trickle as the battery fills with charge and reaches its peak voltage. Inexpensive chargers often work this way. [8]

Two alternative ways of charging are constant current (CC) and constant voltage (CV). As their names suggest, constant current applies a steady current (usually the battery’s peak current), while constant voltage applies a steady voltage (usually the battery’s peak voltage), and the two are often used together, one after another, in constant current constant voltage (CCCV) chargers. Typically, they start off applying a constant current until the battery voltage passes a certain threshold; then they apply a constant voltage until the current passes another threshold. Another variation is two-step constant-current charging that begins with a fast high-current charge and switches to a slower, lower-current charge part way through the process. [9]

Photo: This fast-charge battery charger is designed to charge four cylindrical nickel-cadmium (nicad) batteries in five hours or one square-shaped RX22 battery in 16 hours. I think it’s an example of a constant-current or maybe taper-current charger, though I’ve not tested it to find out. It’s easy to use, and just as easy to misuse: there’s nothing to tell you when charging is complete. With a battery charger like this, charging batteries is complete guesswork.

The final method is called trickle charging. and is similar to constant current charging but uses a much smaller current (perhaps 5–10 percent) for much longer. Some appliances (like cordless phones and electric toothbrushes) are designed to sit on trickle chargers indefinitely.

However you charge, it’s worth remembering that, in a very crude sense, batteries are a bit like suitcases: the more you pack in, the harder it is to pack in any more—and the longer it takes. That’s easy to understand if you remember that charging a battery essentially involves reversing the chemical reactions that take place when it discharges and supplies useful current. In a laptop battery, for example, charging and discharging involve shunting lithium ions (atoms missing electrons) back and forth, from one electrode (where there are many of them) to another electrode (where there are few). Since the ions all carry a positive charge, it’s easier to move them to the empty electrode at the start. As they start to build up there, it gets harder to pack more of them in, making the later stages of charging harder work than the earlier ones.

Graph: Batteries get harder to charge in the later stages. It can take as long to charge the last 25 percent of a battery (red area) as the first 75 percent (orange area). [2] It’s worth remembering this if you have limited time to charge a battery and worry that it’ll take too long: you might be able to charge it halfway in much less time than you think. If the battery in this example takes an hour to charge, you can see that it would reach 50 percent charge (dotted lines) in just 6.5 minutes.

Charging algorithms

Different charging methods are suited to different types of batteries. Simple pulse charging works well for nickel cadmium and nickel metal-hydride batteries, which are also widely charged by the constant current (CC) method, but pulse charging is quite crude and unsuitable for lithium-ion batteries, which are generally charged by CCCV instead.

The cheapest, crudest chargers keep charging your batteries until you switch them off. Forget, and you’ll overcharge the batteries; take the charger off too soon and you won’t charge them enough, so they’ll run flat more quickly. Overcharging is generally worse than undercharging. If batteries are fully charged and you don’t switch off the charger, they’ll have to get rid of the extra energy you’re feeding in to them. They do that by heating up and building up pressure inside, which can make them rupture, leak chemicals or gas, degrade by forming crystals, or even explode. (Think of overcharging as overcooking a battery and you might just remember not to do it!)

Better chargers work more intelligently, combining different types of charging in sequence according to how the battery performs as it’s being charged. So, for example, a battery may be slowly pre-charged (by trickle charging) for a short time to test how well it’s accepting charge, then fast-charged fully by CC and CV, which may be alternated multiple times. [3] The combination of charging methods used by a particular charger is known as its charging algorithm.

Graph: A simple charging algorithm might involve three stages: brief trickle charging to test the battery followed by periods of fast constant-current and constant-voltage charging. [7]

Charging time

The ideal charging time varies for all sorts of reasons (how much charge the battery held to begin with, how hot it is, how old it is, whether one cell is performing better than others, and so on). How does a charger know when to stop? Different methods are used for different types of batteries, and for slow charge or fast charge. The best chargers work intelligently, using microchip-based electronic circuits to sense how much charge is stored in the batteries, figuring out from such things as changes in the battery voltage (technically called delta V or ΔV) and cell temperature (delta T or ΔT) when the charging is likely to be done, and then switching off the current or changing to a low trickle charge at the appropriate time.

There’s usually a primary method of figuring out that the charge is complete (such as measuring the voltage) and one or more backup methods (temperature changes or a preset timer). [4] NiCd chargers, for example, often use a primary method called −ΔV (also written negative delta V or NDV, which refers to the slight voltage drop that a NiCd battery shows just after it’s fully charged), with a backup timer or temperature-change detector. NiMH chargers are more likely to rely on temperature changes as their primary method with a backup timer cut-off circuit. In theory, it’s impossible to overcharge or undercharge with an intelligent charger.

Photo: The Innovations Battery Manager, popular in the 1990s, was sold as an intelligent battery charger capable of recharging even ordinary zinc-carbon and alkaline batteries. Right: A digital display showed the voltage of each battery as it charged (in this case, 1.39 volts). After charging, a little bar graph appeared showing how good a condition the battery was in (how many more times you could charge it). Many thousands of these chargers were sold, but there were differing opinions on how well they worked.

If you’re charging batteries, you probably think fast charge is automatically better—you want to use your laptop or phone as soon as you can. But it comes with major drawbacks. The chemicals in batteries take time to absorb charge and faster charging can shorten the life of a battery (a big problem for things like expensive electric car batteries), or risk safety problems such as overheating and fires. [5]

Multiple batteries

Most chargers are designed to charge two, three, or four batteries at the same time, which adds a few extra complications. If you simply connect them in series and try to charge them, how do you know which batteries are in a good condition and charging well and which ones are poorer and accepting less charge? One battery is almost certain to reach full charge before the others, so it’s almost inevitable that some will be overcharged (and potentially damaged) while others remain undercharged. Decent battery chargers get around this with circuits that monitor each battery individually, switching off or reducing its charging current to a trickle, independently, when it’s fully charged. [6]

AC and DC

Batteries are direct current (DC) devices: current flows in one way (during charging) and out the other (during discharging). But most of us live in homes with alternating current (AC) supplies, so plug-in battery chargers have to convert AC electricity to DC before they can charge the batteries you want to put into them. Exactly how they do this affects the quality of the DC charging current and how cleanly and effectively they charge. Typically, AC-powered chargers use some combination of step-down transformers (to convert high voltages, typically 110–240 volts, to lower ones more like 1.5–20 volts); rectifiers (diode-type circuits) and thyristors (silicon controlled rectifiers), to convert AC to DC; and integrated circuits to filter and smooth their output.

Charging different kinds of rechargeable batteries

To complicate matters, different types of rechargeable batteries respond best to different types of charging, so a charger suitable for one type of battery may not work well with another.

battery, chargers, charger, batteries

Nickel-based batteries

Photos: An electric toothbrush typically contains either nicad or NiMH batteries and slowly or trickle charges on a stand, which is actually an induction charger.

Nickel cadmium (also called nicad or NiCd), the oldest and perhaps still best known types of everyday rechargeable batteries, respond best either to fairly Rapid charging (providing it doesn’t make them hot) or slow trickle charging. [10]

Nickel metal hydride (NiMH) batteries use newer technology and look exactly the same as nicads, but they’re generally more expensive because they can store more charge (shown on the battery packaging as a higher rating in mAH or milliampere-hours). NiMH batteries can be fast charged (on high current for several hours, at the risk of overheating), slow charged (for about 12–16 hours using a lower current), or briefly trickle charged (with a much lower current than nicad), but they should really be charged only with an NiMH charger: a Rapid nicad charger may overcharge NiMH batteries.

Expert opinions seem to differ on whether nickel batteries experience what’s widely known as the memory effect. This is the well-reported phenomenon where failure to discharge a nickel-based battery before charging (when you’re topping up a partly discharged battery with a quick recharge) reputedly causes permanent chemical changes that reduce how much charge the battery will accept in future. Some people swear the memory effort is real; others are equally insistent that it’s a myth. The real explanation for an apparent memory effect is voltage depression. where a battery that hasn’t been fully discharged before charging temporarily thinks it has a lower voltage and charge-storing capacity than it should have. Battery experts insist you can cure this problem by charging and discharging a battery fully a few times more.

It’s generally agreed that nickel-based batteries need to be primed (charged fully before they’re used for the first time), so be sure to follow exactly what the manufacturers say when you take your new batteries out of the packet.

How long should you charge rechargeable batteries?

There are two simple reasons why there are so many different sizes and types of batteries: a bigger battery has more chemicals inside it so it can store more energy and release it for longer; bigger batteries also tend to have more cells inside them so they can produce a higher voltage and current to power bigger things (brighter flashlight bulbs or higher-powered motors). By the same token, bigger rechargeable batteries need charging for longer. The more energy you expect to get out of a rechargeable battery (the longer you expect it to last), the longer you’ll need to charge it (or the higher the charging current you’ll need to use). A basic law of physics called the conservation of energy tells us you can’t get more energy out of a battery than you put into it.

Most people tend to put things on to charge overnight without paying too much attention to exactly what that means—but your batteries will work better and last longer if you charge them for the right number of hours. How long is that? It can be very confusing, especially if you use batteries that didn’t come supplied with your charger. Never fear! All you have to do is read what it says on your batteries and you should find (often in tiny writing) the recommended charging current and charge times. If you have a basic charger, simply check its current rating and adjust the charge time accordingly. Bear in mind what we’ve said elsewhere about matching your charger to your batteries, however.

Photo: Battery science is not rocket science—charging rechargeables is easy if you follow the instructions, generally written on the batteries or the package they came in.

For example, these three ordinary, 1.2-volt nickel-based rechargeables have quite different recommendations:

  • At the top, the white and green nicad battery recommends a slow charge of 60mA (milliamps) for 14–16 hours or a fast charge of 390mA (over six times higher current) for just two hours (2h). The total charge going into the battery is equal to the current multiplied by the time, so multiply the numbers and you’ll get a value of about 800–900 mAh. The battery itself claims its capacity is 0.65Ah (650mAH), but don’t forget that the charging process is not 100 percent efficient: the battery won’t absorb all the electrical energy passing through it. So the amount of charge you’re supplying and the amount the battery will absorb are in the same ball park.
  • In the middle, the silver NiMH battery recommends a charge of 200mA (milliamps) for 7 hours, which gives us a charge of about 1400mAh. Again, the battery itself claims its capacity is lower than this (1000mAH).
  • At the bottom, the green and orange NiMH battery recommends a charge of 63mA (milliamps) for 18 hours, which gives just over 1000mAh. The battery is rated slightly lower (970mAH).

Lithium-ion batteries

Lithium-ion rechargeable batteries are usually built into gadgets such as cellphones, MP3 players, digital cameras, and laptops. Typically they come with their own chargers, which automatically sense when charging is complete and cut off the power supply at the right time. Lithium-ion batteries can become dangerously unstable when the battery voltage is either too high or too low, so they’re designed never to operate under those conditions. If the voltage gets too low (if the battery discharges too much during use), the appliance should cut out automatically; if the voltage gets too high (during charging), the charger will cut out instead. Although lithium-ion batteries don’t show a memory effect, they do degrade as they get older. A typical symptom of aging is gradual discharge for a period of time (maybe an hour or so) followed by a sudden, dramatic, and completely unexpected cut-out of the appliance after that. Read more about how lithium ion batteries work.

Photo: An idiot-proof Canon charger for lithium-ion camera batteries. When the battery needs charging, the camera warns you well in advance. Simply remove the battery (very easy on a digital camera), put it the separate charger unit, and the indicator light shows red, turning green when the battery is fully charged. The whole process is automatic and safe: the camera stops you using the battery before its voltage gets too low; the charger stops you charging it before the voltage gets too high.

Lead-acid batteries

The biggest, heaviest, and oldest rechargeable batteries take their name from their (dilute) sulfuric-acid electrolyte and lead-based electrodes. They’re most familiar to us as car batteries (the initial energy supplies that get a car engine turning over before the gas starts burning), though slightly different types of lead-acid batteries are also used in things like golf buggies and electric wheelchairs.

Photo: Lead-acid car batteries were originally developed in the 19th century, long before nickel- and lithium-based rechargeable technologies came along.

Lead-acid batteries are popular because they’re simple, cheap, reliable, and use well-proven technology that dates back to the middle of the 19th century. Generally they last for several years, though that depends entirely on how well they are maintained—in other words, charged and discharged. They do take quite a long time to charge (typically up to 16 hours—several times longer than they take to fully discharge), and that can lead to a tendency both to undercharge (if you don’t have time to charge them properly before you next use them) or overcharge (if you put them on charge and forget all about them). Undercharging, charging with the wrong voltage, or leaving batteries unused causes a problem known as sulfation (the formation of hard lead sulfate crystals), while overcharging causes corrosion (permanent degradation of the positive lead plate through oxidation, analogous to rusting in iron and steel). Both will affect the performance and life of a lead-acid battery. Overcharging also tends to degrade the electrolyte, decomposing water (by electrolysis) into hydrogen and oxygen, which are given off as gases and therefore lost to the battery. That makes the acid stronger and more likely to attack the plates, which will reduce the battery’s performance. It also means there’s less electrolyte available to interact with the plates, also reducing the performance. From time to time, batteries like this have to be topped up with distilled water (not ordinary water) to keep the acid at the optimum strength and at a high enough level to cover the plates.

Matching the batteries to the charger

Different battery chargers are designed to work in different ways at different speeds, largely to suit different types of batteries. The first rule of battery charging is that a charger designed for one kind of battery may not be suitable for charging another: you can’t charge a cellphone with a car battery charger, but neither should you charge NiMH batteries with a nicad charger. Many modern rechargeable appliances and gadgets—such things as laptops, MP3 players, and cellphones—come with their own, special charger when you buy them, so you don’t have to worry about matching the charger to the battery. But if you buy a packet of generic, rechargeable batteries in a store, it’s important that you buy batteries that suit the charger you have or replace your charger accordingly. Note the voltage and current that the batteries require (it will be marked on the battery package or on the batteries themselves), be sure to choose a charger with the right voltage and current to go with them, and charge for the correct amount of time. If you want to buy yourself some rechargeable batteries but you’re not really sure how to go about matching batteries and charger, go for a combined set—where you buy batteries and charger in the same package.

Photo: Matching the battery to the charger. As the world shifts to more environmentally friendly battery-powered electric cars, we’ll need a lot more properly equipped, conveniently sited charging stations. This one uses photovoltaic solar cells (in the canopy) to charge the vehicles parked below. Photo by Dennis Schroeder courtesy of NREL.

How long do rechargeable batteries last?

Not surprisingly, it depends on how you treat them, store them, and use them. Small rechargeables (like NiCd, NiMH, and lithium ion) typically last hundreds of cycles (you can charge and discharge them that many times), which can mean anything from several years of decent life in a laptop to a decade of use in a portable radio. Treated well, lead-acid car batteries are usually good for thousands of cycles and can easily last 5–10 years in a car that’s driven each day. But if you leave rechargeable batteries in a product you barely ever use, never charge or discharge them, overcharge them, let them overheat, or store them in poor conditions, don’t expect them to last long.

How do you know when it’s time to replace batteries? In something like a laptop, you might notice a lithium-ion battery discharges normally for a time, then suddenly loses all its remaining charge very quickly. If you’re using rechargeable NiCd or NIMH batteries in things like flashlights, you’ll see very gradually reducing capacity and the need to recharge much more often.

Top tips for better battery life

How can you get the best from your batteries? Here are some top tips I’ve found by reading through a variety of battery-expert websites:

  • Rechargeable batteries work best when used regularly. Don’t leave them sitting around in your shed, fully charged or fully discharged for months.
  • Battery experts suggest it’s a good idea to condition or recondition your batteries. This means you regularly let them discharge substantially before recharging if you can (though you don’t need to completely drain them).
  • Match your charger to your batteries. For example, use an NiMH charger for NiMH batteries and be sure the charger uses appropriate voltage and current.
  • Don’t overcharge your batteries. You will damage them.
  • Don’t let your batteries get too hot or too cold, either during charging, storage, or use (it damages them). They will warm up during charging, but if they get really hot, something’s wrong.
  • Don’t skimp on buying a decent, intelligent charger. Your batteries will last much longer if the charger treats them right!
  • Wherever possible, follow the instructions that come with your appliance. For example, the instructions that come with the Roomba® robot vacuum cleaner tell you to leave it docked (sitting on its charger), trickle charging, all the time it’s not being used. If you don’t do this, you’ll find your Roomba loses its charge very quickly (even if you don’t use it) and you may well shorten the battery life.
  • If you use something like a laptop, permanently plugged in, get into the habit of letting it run from the battery, perhaps once a week or so, until it discharges almost completely, to help keep the battery in good condition. You’ll find this helps to extend the life of your battery.

Find out more

On other sites

  • Battery University: Isidor Buchmann’s wonderfully detailed website covers everything you could possibly want to know about virtually every type of battery you can think of.
  • The Electropaedia: Barrie Lawson has a similarly detailed site with an alternative explanation of batteries, energy storage, and related physics.

Books

  • Lead-Acid Batteries: Science and Technology by D. Pavlov. Elsevier, 2017.
  • The Battery: How Portable Power Sparked a Technological Revolution by Henry Schlesinger. Smithsonian Books, 2010. A popular-science book running through the history of batteries from the Voltaic pile to the latest lithium-ion rechargeables.
  • Understanding Batteries by Ronald Dell and David Rand. Royal Society of Chemistry, 2001. A very comprehensive guide covering the history of batteries, the various types, how to choose a battery for a certain application, and the electrochemistry of charging and discharging.

Articles

  • A Glass Battery That Keeps Getting Better? by Mark Anderson. IEEE Spectrum, May 30, 2019. Do batteries that improve with time violate a basic law of physics?
  • It’s Big and Long-Lived, and It Won’t Catch Fire: The Vanadium Redox-⁠Flow Battery by Z. Gary Yang. IEEE Spectrum, October 26, 2017. Are VRFBs the next big thing in battery technology?
  • Potential Hazards at Both Ends of the Lithium-Ion Life Cycle by Mark Anderson. IEEE Spectrum, March 1, 2013. Explores the dangers of manufacturing and recycling lithium-ion batteries.
  • Powerful Chemical Cocktail, With a Drawback by Matthew Waldjan. The New York Times, January 17, 2013. Fire risk is an ever-increasing concern as lithium-ion batteries become more commonplace.
  • Spray-on Rechargeable Batteries Could Store Energy Anywhere by Liat Clark, Wired, 2 July 2012. If we could turn battery components into liquids, we could spray them onto any flat surface to store electrical energy.
  • Virus battery could ‘power cars’: BBC News, 2 April 2009. Scientists at MIT have built a powerful new battery from viruses.
  • Battery that ‘charges in seconds’: BBC News, 11 March 2009. A new way of making lithium-ion batteries could lead to much-reduced charging times.

References

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EBL Rechargeable AA Batteries 2800mAh 8 Pack Review

Here at Charger Harbor, I’ve reviewed a ton of power banks, and as you probably know, portable chargers are some of the best chargers to own. However, there is something that can be more reliable and useful than a portable charger: rechargeable batteries that you put into appliances. Most consumers are too focused on buying single-use AA or AAA batteries, which is a waste of money and bad for the environment.

In this review, I’m looking at these EBL rechargeable AA batteries with 2800mAh capacity. Specifically, I’m reviewing the 8 Pack AA batteries with the charger. I’ve been using these batteries for a few weeks now, and I have to say that it makes a lot more sense to get these rather than single-use ones. Of course, certain batteries perform differently for different appliances, but with them being rechargeable, it’s pretty hard to beat.

Power Capacity

The battery capacity of each of these EBL batteries is 2800mAh, and that is probably the highest that you’re going to find with most other AA batteries that are rechargeable as well. Even Duracell rechargeable batteries have a 2500mAh capacity, so these EBL batteries are doing well.

How to Use these Batteries?

Well, since these are AA batteries, you can use them with nearly any device that requires AA batties to be powered. Toys, remotes, videogame controllers, clocks, and many other devices work great with these batteries. I used these batteries with an Xbox wireless controller, and two batteries have lasted a few weeks for moderate gaming time. The best thing is to swap out the batteries for fully charged ones and immediately recharge the empty ones. It does feel good not having to throw batteries in the trash.

How Recharging the Batteries Work

Included in the box with the batteries is the battery charger with eight slots that can fit AA or AAA-sized batteries. The best part about this battery charger is that they are compatible with EBL Ni-MH rechargeable batteries. However, you can also use other brand rechargeable batteries that are also Ni-MH or Ni-CD, and they will still recharge from this battery charger.

Regarding recharging these EBL AA batteries from 0% to 100%, the included battery charger can get them back to full power within 6 hours. Something important to know is that the battery charger has a 5V/2.0A (10W) max input, so you should use a 10W USB-A port with the charger to get the fastest recharging speed for the batteries.

The accessibility of recharging these batteries is also great because you can use a wall charger or even a power bank to recharge them. After all, the battery charger uses a Micro-USB input port to be powered from. Also, the charger has LED lights above each battery slot; a red light means the battery is still recharging, while a green light means the battery is fully charged. Some batteries may recharge to full power sooner than others, so it’s very helpful to know which battery is fully charged and which one is not.

Battery Efficiency

I ran two battery capacity tests using a separate charger; the charger only allows testing up to four batteries simultaneously. For my first test, I had the discharge rate set to 500mA, which is pretty high. With that, I averaged about a 1926mAh capacity from the batteries, which is low and was about 68% efficiency from these batteries. That said, a high discharge rate would naturally result in lower efficiency, so I ran another battery capacity test with EBL batteries having a 200mA discharge rate. This time, the EBL batteries scored about 90% efficiency, which is much better.

Preview Product Price
EBL Rechargeable AA Batteries 2800mAh 8 Pack and 8-Bay AA AAA Individual Rechargeable Battery. 29.99 Buy on Amazon

Build Quality

I honestly can’t say much about the build quality of these batteries because they’re just batteries. The average consumer won’t know the build quality difference between these EBL batteries Vs. Duracell ones, and it’s something I didn’t take into consideration. As long as these recharge well and are functional, they’re good in my book. On a side note, these batteries feel like any other AA battery brand.

Conclusion

If you want a low-cost and reliable way to use AA or AAA batteries, I recommend these EBL batteries that come with their charger. I’m not sure how these will fair for long-term usage, but it beats buying a pack of single-use batteries and throwing them away after they’re fully depleted.

  • Batteries. ProCyco technology. 1200 Tech, ProCyco (Professional recycle) helps maximize its best power performance while charging. 【For free adapter, please go to Promotion】.
  • Low self-discharge. Embedded seal structure expand the space of crystal lattice, make more room for hydrogen, so EBL batteries will holds 80% power after 3 years benefit from its concentration to low self-discharge project.
  • Independent Battery Charger. Charge any number of AA AAA rechargeable batteries without combination to make your charging easier.
  • USB Input Design. USB Input with multiple Charging Options, is suitable for all kinds of 5V 2A Power supply, like power bank, adapter,(NOTE: Fit for 2.0A adapter only, DO NOT use 1.0A adapter)easy for daily use, more convenient.【For free adapter, please go to Promotion】.
  • Battery storage case. Batteries are packed with battery storage case, easy to storage batteries, very convenient for taking and travelling.

EBL Rechargeable AA Batteries 2800mAh 8 Pack Review

Here at Charger Harbor, I’ve reviewed a ton of power banks, and as you probably know, portable chargers are some of the best chargers to own. However, there is something that can be more reliable and useful than a portable charger: rechargeable batteries that you put into appliances. Most consumers are too focused on buying single-use AA or AAA batteries, which is a waste of money and bad for the environment.

In this review, I’m looking at these EBL rechargeable AA batteries with 2800mAh capacity. Specifically, I’m reviewing the 8 Pack AA batteries with the charger. I’ve been using these batteries for a few weeks now, and I have to say that it makes a lot more sense to get these rather than single-use ones. Of course, certain batteries perform differently for different appliances, but with them being rechargeable, it’s pretty hard to beat.

Power Capacity

The battery capacity of each of these EBL batteries is 2800mAh, and that is probably the highest that you’re going to find with most other AA batteries that are rechargeable as well. Even Duracell rechargeable batteries have a 2500mAh capacity, so these EBL batteries are doing well.

How to Use these Batteries?

Well, since these are AA batteries, you can use them with nearly any device that requires AA batties to be powered. Toys, remotes, videogame controllers, clocks, and many other devices work great with these batteries. I used these batteries with an Xbox wireless controller, and two batteries have lasted a few weeks for moderate gaming time. The best thing is to swap out the batteries for fully charged ones and immediately recharge the empty ones. It does feel good not having to throw batteries in the trash.

How Recharging the Batteries Work

Included in the box with the batteries is the battery charger with eight slots that can fit AA or AAA-sized batteries. The best part about this battery charger is that they are compatible with EBL Ni-MH rechargeable batteries. However, you can also use other brand rechargeable batteries that are also Ni-MH or Ni-CD, and they will still recharge from this battery charger.

Regarding recharging these EBL AA batteries from 0% to 100%, the included battery charger can get them back to full power within 6 hours. Something important to know is that the battery charger has a 5V/2.0A (10W) max input, so you should use a 10W USB-A port with the charger to get the fastest recharging speed for the batteries.

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The accessibility of recharging these batteries is also great because you can use a wall charger or even a power bank to recharge them. After all, the battery charger uses a Micro-USB input port to be powered from. Also, the charger has LED lights above each battery slot; a red light means the battery is still recharging, while a green light means the battery is fully charged. Some batteries may recharge to full power sooner than others, so it’s very helpful to know which battery is fully charged and which one is not.

Battery Efficiency

I ran two battery capacity tests using a separate charger; the charger only allows testing up to four batteries simultaneously. For my first test, I had the discharge rate set to 500mA, which is pretty high. With that, I averaged about a 1926mAh capacity from the batteries, which is low and was about 68% efficiency from these batteries. That said, a high discharge rate would naturally result in lower efficiency, so I ran another battery capacity test with EBL batteries having a 200mA discharge rate. This time, the EBL batteries scored about 90% efficiency, which is much better.

Preview Product Price
EBL Rechargeable AA Batteries 2800mAh 8 Pack and 8-Bay AA AAA Individual Rechargeable Battery. 29.99 Buy on Amazon

Build Quality

I honestly can’t say much about the build quality of these batteries because they’re just batteries. The average consumer won’t know the build quality difference between these EBL batteries Vs. Duracell ones, and it’s something I didn’t take into consideration. As long as these recharge well and are functional, they’re good in my book. On a side note, these batteries feel like any other AA battery brand.

Conclusion

If you want a low-cost and reliable way to use AA or AAA batteries, I recommend these EBL batteries that come with their charger. I’m not sure how these will fair for long-term usage, but it beats buying a pack of single-use batteries and throwing them away after they’re fully depleted.

  • Batteries. ProCyco technology. 1200 Tech, ProCyco (Professional recycle) helps maximize its best power performance while charging. 【For free adapter, please go to Promotion】.
  • Low self-discharge. Embedded seal structure expand the space of crystal lattice, make more room for hydrogen, so EBL batteries will holds 80% power after 3 years benefit from its concentration to low self-discharge project.
  • Independent Battery Charger. Charge any number of AA AAA rechargeable batteries without combination to make your charging easier.
  • USB Input Design. USB Input with multiple Charging Options, is suitable for all kinds of 5V 2A Power supply, like power bank, adapter,(NOTE: Fit for 2.0A adapter only, DO NOT use 1.0A adapter)easy for daily use, more convenient.【For free adapter, please go to Promotion】.
  • Battery storage case. Batteries are packed with battery storage case, easy to storage batteries, very convenient for taking and travelling.

The best rechargeable battery chargers in 2021

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  • The best rechargeable battery chargers are simple to use and don’t overcharge your batteries, preserving their lifespan.
  • The Nitecore D4 Charger is our top pick because it doesn’t overcharge, has a large display, and can auto-detect a wide array of batteries.
  • Also check out our guide to the best rechargeable batteries you can buy.

It’s estimated that Americans dispose of 3 billion batteries every year, according to battery recycling firm Battery Solutions. But rechargeable batteries can be reused 1,000 times or more, which is better for the environment and your wallet in the long run.

However, rechargeable batteries can become damaged over time with the wrong kind of charger. For example, don’t pick a charger based on charging speed alone. High-speed charging can severely shorten the lifespan of your batteries. Instead, look for a charger that offers gentle or slow charging.

If you are concerned about having to wait for the charging to complete before using your device again, consider buying a couple of sets of batteries for the device. Some chargers also have a conditioning function. This cycles your batteries through discharging and recharging in order to help them reach their full capacity and lengthen their life.

Smart chargers can also stop charging your batteries once they are full as opposed to less effective dumb chargers, which tend to charge for a certain amount of time.

While researching the best rechargeable battery chargers, we examined thousands of expert and buyer reviews and ratings of several models. Our guide features chargers with a track record of versatility, durability, and performance.

Here are the best rechargeable battery chargers:

Updated on 3/04/2021 by Antonio Villas-Boas: Refreshed existing language for legibility and brevity, and checked all and links. We’ll further update this article accordingly as we test more rechargeable battery chargers.

The best overall

The Nitecore D4 Charger can charge an array of battery types, while displaying the charge progress on an easy-to-read LCD panel.

Pros: Large display, charges a broad range of battery types, automatic battery detection

battery, chargers, charger, batteries

Cons: Only displays the progress of one battery at a time, charge time increases when charging four batteries

The Nitecore D4 Charger is great because it can automatically detect and charge Li-ion, LiFePO4, Ni-MH, and Ni-Cd (AA, AAA, AAAA, and C) batteries. This device can charge up to four batteries at a time, and the large LCD screen displays the progress of the charge for each of the batteries using a five-bar indicator.

For specific batteries, you can press the Mode button on the side to get more detailed charging progress and parameter information, such as charging time, current, and voltage.

When the charge is complete, the Chg. Finish indicator comes on and the D4 automatically stops charging, an important safety feature. The bundle comes with the charger, a wall plug, and four EdisonBright AA NiMH rechargeable batteries.

The most common complaint is that recharging slows when there are four batteries charging.

battery, chargers, charger, batteries

The best 8-cell battery charger

If you frequently use AAs and AAAs in your electronics, the Powerex MH-C800S 8-Cell Smart Charger will keep your batteries juiced and extend their life.

Pros: 8 charging slots, features conditioning cycle

Cons: Expensive, only charges AA and AAA batteries

The Powerex MH-C800S 8-Cell Smart Charger is manufactured by Maha Energy, an organization that focuses solely on charging and battery technology for both consumer and industrial sectors.

The MH-C800S can charge between one and eight NiMH or NiCd AA or AAA batteries. The LCD screen uses three bars to show the charging status of each battery. There are three charge modes: Rapid charge (one to two hours), soft charge (three to four hours), and conditioning, which can take a full day.

Wirecutter previously recommended the Powerex charger for people who need eight charging slots on one outlet. The reviewer appreciated the accurate charging, that you can monitor the progress, and it’s easy to use. However, he didn’t like that the default mode is the faster 1-A charging, which isn’t as conducive to extending your battery’s lifespan as the Soft charge.

The best battery charger for vaping

At a relatively low price point, the XTAR VC4 Charger is able to charge a wide range of battery sizes and types.

Pros: Charges several different battery types, cost-effective, USB power input

Cons: Doesn’t come with a USB wall adapter, it takes some work to fit AAA batteries in

There are a couple of features that set the XTAR VC4 Charger apart from other devices in our guide. First, it doesn’t plug directly into the wall. The charger features a USB charge cable, which you can plug into just about anything with a USB port. I use a multiple-port USB wall adapter. Another unique feature is that the slots are large enough to fit D-cell batteries. It’s fairly rare to find a unit that can handle NiMH cells ranging from AAA to D.

XTAR sent me the VC4 for free to test out, and for the most part my family has been happy with it. I use it for charging NiMH batteries for a variety of devices, including my sons’ toys, and my wife uses it for her vaporizer’s 18650s.

I’ve found that it’s a real pain trying to get the AAA batteries in there just right to get them to charge. Other sizes seem to work fine, though. The display is easy to read and gives helpful information that even a layperson can understand, but it can be finicky when you first insert the batteries.

The best for AA and AAA batteries

If you are mainly in need of a good charger for AA and AAA batteries and don’t need a fast charge, consider the affordable Panasonic Advanced Individual Cell Battery Charger Pack.

Pros: Uses slow charge to extend battery life, simple to use, inexpensive, comes with batteries

Cons: Only charges AA and AAA batteries

The Panasonic K-KJ17MCA4BA Advanced Individual Cell Battery Charger Pack is unique in its simplicity. You just pop in one to four AA or AAA batteries (any combination will work) and wait for the charging light to turn off. The batteries charge at a slower 300 mA speed, which is great for extending their lifespan. And, when charging is complete, it automatically shuts off.

There are four different packs that vary based on what batteries come with it. There are the packages that come with four AA or four AAA batteries. The Power Pack comes with 8 AA, 2 AAA, and 2 C-size and D-size spacers. You simply put an AA battery in the spacer when you want to power devices that require C or D cells. The Super Power Pack is essentially the same as the Power Pack, only it has 12 AA and 4 AAA batteries along with the spacers. The charger is the same for all four packages.

The Panasonic Advanced Individual Cell Battery Charger was previously the top pick on Wirecutter. The reviewer liked how simple it is to use and that you can charge just one battery, rather than having an even number in the slots. For the typical NiMH AA battery, he found it took about seven hours to reach a full charge.

Check out our other related buying guides

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Joe was a Senior Tech Editor for Insider Reviews with more than a decade of experience in games and tech media. His work has appeared in TechRadar, PC Magazine, Laptop Magazine, Tom’s Guide, AOL’s Games.com, and more. Joe has also appeared as a tech expert on programs such as Cheddar from the floor of the New York Stock Exchange as well as on panels of experts for events such as CES. His specialties include computing as well as gaming products using a variety of operating systems and interfaces, not to mention extensive benchmarking experience. Learn more about how our team of experts tests and reviews products at Insider here. Learn more about how we test tech and electronics.

Antonio is a senior tech reporter for Insider’s Reviews team, where he helps lead coverage, reviews, and guides of smartphones, tablets, accessories, wearables, Smart home products, as well as audio devices from Apple, Google, Samsung, OnePlus, and other major tech companies. Before joining Business Insider, Antonio was a consumer-electronics analyst at PCMag. He graduated from Colgate University in 2009 with a bachelor’s degree in history. You can contact Antonio with tips and cool tech via email at: avillasboas@businessinsider.com Learn more about how our team of experts tests and reviews products at Insider here. Learn more about how we test tech and electronics.

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