How to Choose Best LiPo Battery for your Drone | Quadcopter 4S | 3S | 2S | 1S
Batteries for your quadcopter have a few more areas of consideration than simply how long it will keep your craft in the air. This guide is to help inform you of what those considerations are, and to help you decide which is the best lipo battery for your drone and individual style of flying.
Voltage and capacity are the most important things to consider, but weight and discharge rate (also called ‘C’ rating) are almost as important.
LiPo Battery Basics
As we know from Christmas mornings as kids, not all batteries are the same. After unwrapping the biggest gift under the tree, and fitting the “no-name” batteries that came free with your toy, the buzzing and beeping, that drives parents to distraction, gets quieter and more distorted, until the batteries no longer work at all. We learn pretty early on that it is worth spending a few extra on good quality batteries so our play time doesn’t get cut short.
Battery Voltage (Cell count)
The nominal voltage of a LiPo cell is 3.7v, cells are put together in series to increase the voltage, the number of cells used in a LiPo pack is shown by a number followed by the letter ‘S’. So a 2S battery has 2 cells wired together in series to create a 7.4v battery, and a 3S has 3 cells to increase the voltage to 11.1v. The most common voltage for quads at the moment is a 4S 14.8v battery.
Capacity
The capacity of a LiPo has the greatest effect on flight times, the higher the capacity, the longer the flight time you will get from your craft, but the higher the capacity, the heavier the battery will be. As the LiPo is the single heaviest component on your quad, you will reach a stage where you get diminishing returns, and the battery is too heavy for your craft to carry efficiently. The most common capacity for racing drones with 5 inch propellers is 1300mAh, which seems to find the best balance between performance, flight time and weight, but there are, of course, exceptions to this.
Discharge Rate (C Rating)
The discharge rate is shown by a number followed by the letter ‘C’, the higher the discharge rate, the better. The discharge rating shows how quickly you can safely discharge your battery. A higher C rating means that you will use less throttle input to get your craft to hover, and it will provide more amperage to the motors at full throttle, making your craft faster and more punchy.
There is a phenomenon known as ‘Voltage Sag’. The higher your throttle input, the faster you deplete your battery, but this depletion is not linear. At very high throttle the voltage drops even faster, but as you decrease throttle, the voltage will recover, the lower the C rating of your battery the more pronounced the voltage sag will be, and the longer it will take for the voltage to increase again.
With a high C rating, the voltage drop at very high throttle will be reduced. I recommend 45C as the very minimum to fly slowly, a 75C pack will be better for freestyle, but to get the best out of your quad, and particularly for racing you should be looking at C ratings of 80-100C and higher.
Note. Batteries with a higher C rating will usually be slightly heavier, than others with the same voltage and capacity.
Buyers tip. Some manufacturers inflate the numbers of the C rating of their batteries, which is why it is recommended to purchase your batteries from a reputable source.
Important Buyers Note. Unscrupulous manufacturers often inflate the advertised C ratings of their batteries, as such it is highly recommended to purchase batteries of a well known brand from a reputable retailer.
Battery Chemistry
Batteries store electrical energy by using a reaction between different chemicals, such as Lead and Acid. which is what is used for car batteries. Li-Po or Lithium. Polymer have a good power density, they can be made in various shapes and also inherently have good discharge rates, which make them ideal for our hobby/sport.
There are 2 other common chemistry types used for drones, these are LiHv (Lithium High Voltage) and Graphene. LiHV cells have a higher nominal voltage of 3.8v per cell, which provides a little more punch at full charge. Graphene batteries are said to have a slightly longer lifespan as they build internal resistance slower than a standard LiPo or LiHv.
Batteries don’t last forever
Like propellers, LiPo batteries are a consumable in the hobby, however they should last longer than your props, as long as you treat them well! I mentioned internal resistance earlier, this is what kills your batteries over time. The more you use a LiPo, the more the internal resistance increases. Internal resistance can be thought of as a component within your battery that uses electrical energy, leaving less power for your motors.
Over charging, and over discharging your batteries will cause internal resistance to increase more quickly, also leaving your batteries fully charged or discharged (past 3.2v per cell) for extended time periods will also cause internal resistance to build faster. Unless you are going to fly tomorrow, I would recommend that you re-charge/discharge your batteries to storage voltage, which for standard LiPo, LiHv and Graphene batteries is between 3.7 and 3.95v per cell, most say 3.8v for LiPo and Graphene and 3.85v for LiHv.
Best Lipo Drone Battery
Tattu R-Line
High End Lipo Batteries
Tattu R-Line
Experienced FPV pilots prefer using the Tattu LiPo batteries, which cost almost twice as much when compared to a GNB or CNHL battery pack. The reason being. The performance offered by these packs is top level.
Tattu batteries have been in the market for quite a while, and are on their 5th iteration, refining the design and build quality over the years. Tattu claims to use an exclusive technology called Al Boehmite, which will offer a significant improvement in overall performance and continuous power output. The new technology claims to provide the power consistently and continuously and offer a very minimal decrease in performance after a charge–discharge cycle. These batteries are lauded because they can handle the voltage sags better than the other competing battery packs. They usually are true to their battery capacity, meaning the mAh rating is not bloated for marketing purposes. If you want the ultimate performance a LiPo can offer, then just add 10 of these batteries to your cart and buy them. You won’t regret it. But the question you ask yourself is, Do I need that much power? Most pilots are casual flyers and do just fine by using the cheaper Chinese packs. Tattu is suited more for hardcore flyers.
CNHL Lipo Drone Batteries
Best Budget Pick
Best Budget Pick
CNHL Lipo Drone Batteries
China Hobbyline (CNHL) is another Chinese Lipo manufacturing brand. Like the GNB batteries, the CNHL batteries also suffer from reduced power output and are slightly larger and heavier in comparison to other brands of similar capacities.
In terms of performance the CNHL batteries are good budget option. Cells are generally balanced and are matched with lower IR. At times, I really put Lipos through some torture and the CHL packs seemed to take it in stride! What makes them racing spec is that they weigh less and general rule is if you have two lipos with same cell count, mAh and C rating the heavier one will be better in terms of performance life. I rate them as budget mid ranger mainly as you can almost buy 2 for the price of a 1 Tattu and have yet to have one go bad. Also you can get the same flight times as with Rebel batteries ie. which are almost triple the price. They can put up a lot of damage and still work. Cells all measure the same and charges/discharges perfectly. Had about 30 charges since it got splatted against a tree and went flying. Can’t fault it.
Gaoneng Lipo Batteries
Cheapest worth having
Cheapest worth having
Gaoneng Lipo Batteries
GNB Batteries are one of the most popular battery choices amongst pilots, thanks in part, to their dirt-cheap price and acceptable performance. They come in various shapes and sizes, all the way from 1. 8S voltages with varying capacities.
These batteries are sometimes, during sale days, priced at half the price when compared to the premium offering on our list. The cheap price makes these batteries expendable and the loss of one doesn’t hurt the wallet as much. The downside is, that the GNB packs do not perform as per their advertised capacities, ie., To further add to the wound, GNB is based out of China and shipping takes a loooong time. Generally, GNB batteries are slightly larger and heavier than other brands in their class. But since these batteries are mostly preferred by beginners and intermediate pilots, the slightly lower performance offered by these packs wouldn’t be a deal-breaker.
RDQ LiPo Batteries
Best Value for Money
Best Value for Money
RDQ LiPo Batteries
RaceDayQuads LiPo batteries are exclusively sold by RaceDayQuads. RDQ is based in the United States, and what this means is that they will not take 2 months to reach you
All RDQ batteries command a slight premium (usually a few dollars, and RDQ has offers running during certain times of the year) over their comparable Chinese counterparts. In hindsight, the RDQ packs are of higher quality and last longer. The RDQ LiPos perform exceptionally well in real-world tests, with Joshua Bardwell claiming in his tests that these batteries performed close to some premium batteries. If Joshua says the battery packs are good, it is safe to assume that these packs have what it takes to get the job done. These packs come in voltages from1- 6S and various capacities to fulfil the needs of every pilot.
V LiFePO4 Battery Voltage Chart
Here’s a printable version of the above chart:
And here it is graphed out:
12V 100Ah LiFePO4 batteries are currently some of the most popular for off-grid solar power systems. They’re a drop-in replacement for 12V lead acid batteries, and a great upgrade.
They are fully charged at 14.6 volts and fully discharged at 10 volts. They are made by wiring four 3.2V LiFePO4 cells in series.
12V LiFePO4 Battery Charging Parameters
- Charging voltage: 14.2-14.6V
- Float voltage: 13.6V (or disabled)
- Maximum voltage: 14.6V
- Minimum voltage: 10V
- Nominal voltage: 12V or 12.8V
V LiFePO4 Battery Voltage Chart
Here’s a printable version of the above chart:
And here it is graphed out:
24V lithium iron phosphate batteries are another popular option for DIY solar power projects. You can either buy a 24V LiFePO4 battery off the shelf, or get two identical 12V LiFePO4 batteries and connect them in series to make a 24V battery bank.
They are fully charged at 29.2 volts and fully discharged at 20 volts. They are made by connecting eight 3.2V LiFePO4 cells in series.
24V LiFePO4 Battery Charging Parameters
- Charging voltage: 28.4-29.2V
- Float voltage: 27.2V (or disabled)
- Maximum voltage: 29.2V
- Minimum voltage: 20V
- Nominal voltage: 24V or 25.6V
V LiFePO4 Battery Voltage Chart
Here’s a printable version of the above chart:
And here it is graphed out:
48V batteries are more popular for larger solar systems. They rarely make sense for small-scale projects. Designing a higher voltage solar system allows you to keep amperage low, thereby saving you money on wiring and equipment costs.
48V LiFePO4 batteries are fully charged at 58.4 volts and fully discharged at 40 volts. They are made by connecting 16 3.2V LiFePO4 cells in series.
48V LiFePO4 Battery Charging Parameters
- Charging voltage: 56.8-58.4V
- Float voltage: 54.4V (or disabled)
- Maximum voltage: 58.4V
- Minimum voltage: 40V
- Nominal voltage: 48V or 51.2V
Step 2: You’ll Need a Smart Charger
I’m not going to go into the details of LiPo balancing chargers, but you’ll definitely need a nice charger that can balance multi-cell packs and which has the ability to control the charge current.
Here are some links to get your started:
Note: if shipping speed and customer service are a high priority, just jump straight down to #4 in the list below to look at the Amazon prime LiPo charger options in the search results. 1) http://electricrcaircraftguy.com/2013/02/thunder-ac680-computer-data-logging.html. I highly recommend this charger; it works great and has an outstanding value. Comparable chargers to this at many other retailers cost at least 2x more. 2) Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories. also an outstanding, and dirt-cheap, yet highly functional Smart charger. Excellent value; however, it requires an external power supply, such as this: Hobbyking 105W 15V/7A Switching DC Power Supply. 3) http://www.hobbyking.com/hobbyking/store/216408Chargers_Accessories-Battery_Chargers.html. general list of chargers; be sure to READ THE REVIEWS!
4) And last but not least, don’t forget Amazon! Here’s the results for an Amazon search for LiPo Charger. Check this list out for sure, as you get Amazon’s excellent shipping speed and customer service too!
Step 3: Important Instructions Just Before You Begin Charging the Over-discharged LiPo
LiPo-safe charging bags can be purchased in many places, but Amazon always has a good selection and super fast shipping, so take a look at Amazon’s search results for LiPo charge bag here.
Step 4: Begin the Charge (LiPo Is
Example: for the LiPo battery shown at the top of this instructable, a 1/20 C charge rate would be 1/20 x 1.3Ah = 0.065A. This is because the battery’s capacity, as stated on the label, is 1300mAh (read as mili-amp-hours), or 1.3Ah (read as amp-hours). So, a 1/20 C charge rate is 1/20 of 1.3, or 0.065A. A 1/10 C charge rate is 1/10 x 1.3 = 0.13A. Note that although some Smart chargers can charge at currents as low as 0.05A, many cannot charge at a rate lower than 0.1A. If you cannot set your charger to charge at a current as low as you’d like, simply choose its lowest setting possible, and carefully monitor the battery during the charge.
Additional Charge Setting Notes: recharging a LiPo below 3.0V/cell may require using a NiMh or NiCad charger setting on the LiPo batteries, as most Smart chargers have safety features which prevent a user from attempting to charge a LiPo which is below 2.5V/cell, as this can be dangerous if a standard charge rate is used. Since all we are after is setting a low (and safe) constant charge current to get the LiPo back up to a safe charge level, using a NiMH/NiCad setting is fine until we get the battery 3.0V/cell. WHEN USING AN NIMH or NiCad SETTING TO GET THE LIPOS ABOVE 3.0V/CELL, NEVER LEAVE THEM UNATTENDED. You should not leave them unattended because the NiMh/NiCad end-of-charge detection method is not compatible with Lithium based batteries, and if left on the charger until full, the end-of-charge state will never be detected and the LiPo battery will be overcharged until it (likely) catches fire and destroys itself.
LiPo Storage
Unlike “regular” batteries, LiPo batteries have pretty specific storage requirements. In an ideal world, you wouldn’t store them in your home or garage, due to the fire risk. However, in the “real world” this isn’t always possible.
Let’s see how we can safely store and transport our LiPo batteries.
Storage Voltage
You should never store a fully-charged LiPo battery. Instead, it should be brought down to “storage voltage”, which is 3.8 to 3.85 volts per cell.
There are a few ways you can achieve this.
If the LiPo cells are currently under 3.8-volts then you can charge them up to this level. Most good LiPo chargers have a Storage function, which will raise the cells to 3.8-volts.
If the cells are still charged above 3.8-volts, then you will need to drop them down to that level. Again, many chargers have a function to do this, but it can take a very long time to reduce the voltage, especially if they are near a full charge.
Another method is to put them back in your device and run them down to that level, or just below it, so you can top them up in the charger.
You can also use a resistive load to drain the batteries, a 20 – 40 ohm power resistor is a good choice. The resistor should get warm, but not too hot, and the battery should remain cool. Depending upon how charged up they are, it may take some time to complete the drain down to 3.8-volts.
If you do need to bring them up or down to storage voltage, be sure to observe all the safety tips from the charging section, and never leave them unattended.
LiPo Battery Bags
If you search for LiPo storage, there is a good chance that you’ll come up with a number of “LiPo Bags”.
These bags purport to be both explosion and fire-resistant, and on the surface, it sounds like they would be all you would need to safely store your batteries. But the truth is, they aren’t all that they are advertised to be.
These bags are made of cloth, usually with a metallic compound woven into them. They generally have either a zipper or a Velcro fastener, and they come in a wide assortment of sizes.
But despite their somewhat grandiose claims, they really can’t withstand the heat of a LiPo fire. At best, they will slow it down enough to allow you to grab your extinguisher. But left alone during a fire, they will quickly break down.
Now, don’t get me wrong, these LiPo bags do have their use. I use them when I’m charging a LiPo, an operation that is always supervised and for which a fire extinguisher is on hand. And I also use them to supplement my other storage solutions. And they are great for transporting a LiPo from its storage area to the device you are powering.
But, on their own, they don’t offer adequate safety, and shouldn’t be the only thing you rely upon to protect you from a LiPo that experiences a thermal runaway.
Using a Cinder Block
A very popular method of storing LiPo batteries is to use a cinder block. These are pretty inexpensive and are made of cement, so they can provide a lot of fire protection.
In practice, you just place the LiPo batteries inside the “hole” in the cinder block. For added protection, you can place the batteries inside a LiPo bag before inserting them into the cinder block.
You can also cover the cinder block with a piece of steel or drywall for added security.
Using an Ammo Box
One excellent and inexpensive method of storing LiPo batteries is to use an ammo box. These containers are made of steel and, as such, offer exceptional fire protection. They are available at sporting goods stores, as well as at Amazon.
Before you use the ammo box, you need to make one modification. These boxes have a rubber seal on the lid, whose purpose is to render the box both air and watertight. But for a LiPo storage container, having an airtight enclosure is the last thing you would want. LiPo batteries can vent gas, and if the gas can’t escape, the pressure could build up to a dangerous level. If it ignites, then you have yourself a bomb!
Always remove the rubber seal from an ammo box before using it as a LiPo storage box! The seal is generally very easy to remove, I used a screwdriver to pry it off the box I’m using.
Some users also drill some small holes in the box (you need a good sharp drill to penetrate steel) to allow for more airflow, but taking off the seal should suffice.
You can also put your LiPo inside a battery bag within the box for added protection.
My Homemade LiPo Storage Box
I built a storage container for my LiPo batteries, you can see the details in the video that accompanies this article.
LiPo Fire Extinguishing
I sincerely hope that you never experience a LiPo fire, it is a fast-burning and very hot fire that can be extremely dangerous, especially as it is often accompanied by a toxic outgassing of burning chemicals.
But even if you take every precaution, it can happen, due to an accident or a defective LiPo. In that situation, you need to be prepared to extinguish that fire as quickly as possible.
LiPo Fire Risk
A LiPo battery can experience thermal runaway, a condition in which the heat continues to increase unabated. This can be caused by several things:
- Charging a battery that has an excessive Internal Resistance in one or more cells.
- Charging a damaged, defective, or ballooned battery.
- Exposing a battery to excessive heat. Try and keep it under 60 degrees Celsius.
- Excessive shock or pressure, such as in a crash.
Note that the majority of times thermal runaway occurs during the charging process, so it’s important to be prepared for a fire when charging your LiPo battery.
Another risk is that a LiPo that is experiencing thermal runaway may vent toxic gas, which can also explode if ignited. This is why you should always charge a LiPo in a well-ventilated area, preferably outdoors.
Extinguishing a LiPo Fire
Despite its name, a Lithium-ion Polymer Battery actually has very little lithium inside it. The small amount of lithium will react with water, but it is usually burned off within seconds at the start of the fire event. By the time you realize you have a fire, the lithium will likely be gone.
Because of this, it is NOT necessary to obtain a Class D fire extinguisher, which is the type normally recommended for a lithium fire. They are expensive and hard to use.
Instead, a standard Class ABC extinguisher can be used. This is something you should have around your workshop anyway, so you probably already own one. If not, they can be obtained and just about any hardware store.
You can actually use water during a LiPo fire, but it is best used to hose down the area around the burning battery to prevent it from igniting. Often the biggest danger from a LiPo fire is the items surrounding the battery that catch fire. Another great reason to charge your LiPo away from such items!
A great way to quickly extinguish a LiPo fire is with sand. A bucket or bag of sand is pretty easy to obtain, and you can smother the fire with it.
The accompanying video has some scenes of LiPo fires, to give you an idea as to what you would be up against if you had one. After watching it, you should have a new appreciation for the necessity of preparing for a LiPo fire!
LiPo Disposal
All batteries have a limited lifespan, and LiPo batteries are no exception. If handled correctly, these batteries can last for 350 to 500 charge and discharge cycles, but eventually, they will require replacement.
When they do come to the end of their useful life, they need to be discharged and properly disposed of.
Determining when your LiPo needs Replacement
If you’ve taken care of your LiPo batteries then they should last a pretty long time, as stated above you should be able to get at least 350 uses out of them.
But if you have abused them by not keeping them balanced or stored properly (at 3.8-volts per cell), or if they have been damaged, then they may not last as long.
If you’re tracking the internal resistance of the cells and notice a sudden increase, then it’s a sign that the LiPo is near the end. If the battery gets warm under normal use, if it is ballooned, or if it fails to hold a charge or stay balanced, then it’s time to replace it.
Discharging a LiPo Battery
Before you can dispose of your LiPo battery, it needs to be completely discharged. Even a “dead” LiPo can hold a lot of energy, and it can catch fire if crushed in a garbage truck or trash compactor.
Many quality LiPo chargers have a “Discharge” or “Destroy” function that will completely drain the battery. The procedure can take several hours, or even more than a day, depending upon how much energy is left in the cells.
Another way of draining a LiPo is to use an automobile taillight or a resistive load, leave it on the LiPo for a day, and then measure the output voltage. If it is more than zero, then put the load back on for a few more hours. Keep going until no electricity can be detected.
One method that many RC hobbyists use is to soak the entire cell in a saltwater bath for a day or two. You can also do this after draining the battery with one of the above methods, to ensure that it is completely depleted of energy. Table salt will work fine, you need to saturate the water until it can’t hold any more salt.
Disposing of a LiPo Battery
After discharging the battery completely, you can dispose of it.
In many municipalities, you can simply throw it in with the rest of your trash, as it no longer contains any volatile or dangerous chemicals and has very little lithium. But in some areas, you will need to take it to an authorized disposal facility.
Make sure you check with the proper authorities to determine the proper disposal method for your area. In my community, we have a bi-annual hazardous goods disposal at the city hall, and they take all batteries, including LiPo batteries.
Conclusion
When it comes to using LiPo batteries, nothing is more important than safety. Fortunately, it doesn’t take a lot of effort to observe the proper safety precautions, minimizing the chance of a dangerous fire or outgassing.
LiPo batteries are powerful devices that need to be treated with respect and handled with care. If you observe proper handling, charging, balancing, and storage techniques, these batteries can last a long time and provide a virtually unlimited source of power for your projects.
Parts List
Here are some components that you might need to complete the experiments in this article. Please note that some of these links may be affiliate links, and the DroneBot Workshop may receive a commission on your purchases. This does not increase the cost to you and is a method of supporting this ad-free website.