If you want the best for the RC craft you’re piloting (and who doesn’t?), you need to explore lithium polymer LiPo batteries. Most of you already know the benefits of a LiPo battery. Yet some of the new comers to our wonderful hobby have some questions and we have seen some of you old timers mishandling your LiPo batteries.
RC planes used to be advanced if they took NiMH batteries, as expensive and heavy as those were. While they packed a punch, they took away from the speed and lift you’d hope to get from your RC plane. Even fabled Warbirds and Air Hogs saw some negative effect from them. The change to LiPo, while still more expensive, does away with a lot of those downsides. But, LiPo batteries come with special care requirements. We want to set the record straight and give you the information you need to be an informed hobbyist so that you can get the most from your RC experience!
Some Science: What is a LiPo Battery?
LiPo batteries (or lithium polymer batteries) are based on lithium polymer ions. These batteries are constructed of a gel, under a stacked anode and cathode. But if you are you’re standing in the battery aisle holding a LiPo battery in one hand and a Lithium Ion battery in the other, that bit of trivia won’t be very helpful!
Essentially, these two types of batteries are the same chemical. But, a LiPo battery has a non-flammable gel while a Lithium Ion battery uses an electrolyte gel. So, basically, the Lithium Ion batteries are more likely to overheat than a LiPo is; which is why we use LiPos in our planes! Yet, LiPos have their safety concerns as we will soon see.
How to charge a LiPo battery
LiPo batteries also have a fairly long life span in comparison with Lithium Ion models and their NiMH predecessor. Lithium Ion batteries begin power decay as soon as they’re made and will, at most, last two to three years. A LiPo battery pack will be rechargeable and will last at least 300 to 400 charge cycles. For some of you pilots out there, this may be one long weekend of flying! (just kidding!) So, let’s start by looking at what you need to know about charging them.
- First, look over the batteries before you charge them. Make sure the batteries aren’t discolored, swelling or warm in spots.
- Charge them slowly. Really. Cheap LiPo battery chargers often go as high as 5C (five times capacity). For LiPos, you want to start with around 1C. At most you want to use 2C with a balancer.
- Why a balancer? LiPo battery packs contain more than one cell. If you’re not manually setting the cell number on your charger (and you shouldn’t have to with a good quality charger), you’re risking your charger only detecting the total voltage and not the number of cells you’re charging. Doing this with LiPo batteries can result in uneven charging of the cells, undercharging some cells, and overcharging others. This kind of unbalanced charging can make a LiPo battery explode or cause a fire. Take the time to make sure your charger settings match those recommend for the battery pack.
- In addition to making sure you’re charging your LiPo batteries with a balancer, you should always charge them on a fireproof surface or in a fireproof container.
- Don’t ever leave LiPos unattended while they’re charging.
- It’s also recommended to make sure there’s a working smoke detector in the room where you’ll be charging the batteries.
- If, by some chance, you do experience a LiPo battery fire, do not attempt to put the fire out using water. Use a fire extinguisher or sand (dirt) to smother the flames.
How to Condition a New LiPo Battery
The only true way to get 300-400 cycles from your LiPo battery is to properly condition and care for your LiPo batteries. Even if your LiPo batteries have some charge when you get them, you should cycle them through, charging and discharging them around three times. Make sure you condition the batteries before you use them in your plane. You’ll get more life out of them this way. A fully charged cell will store 4.2 volts. A word of advice, though: don’t store your batteries at 100% charge. We will tell you why in a moment.
How to Care for LiPo Batteries
LiPo battery care is not difficult. It just requires more attention than you may be used to giving to other types of batteries you’ve used with your RC aircraft.
- First, don’t let children touch your LiPo batteries. Dropping them can be all it takes to create a hole in one of the cells which is more than enough to cause an explosion and/or a fire.
- Always check your batteries for any swelling. This is especially important when you’re getting ready to charge a LiPo battery pack.
- Careful handling and attention to the capacity your batteries have even when you’re not using them are among the cardinal LiPo battery care rules.
- If you do puncture your batteries and the gel gets on your skin, don’t panic, just wash the gel off with soap and water as soon as possible.
When your LiPos are being stored, you should only have them at 50% charge level. Storing your batteries with either more or less than that can drastically affect its lifetime.
- Store your batteries in a LiPo battery safety bag and put them in a cool, dry place. A pantry shelf or in a closet will work well for that.
- Even though cool temperatures are recommended for LiPo battery storage, don’t freeze your batteries as this will damage them.
- And, just as you shouldn’t charge your batteries near something flammable, you should not store them near flammable items or fuel. (We hear stories of people keeping them in the truck of their car…this is a No, No!)
As you use your LiPo batteries, you should take care not to run them consistently above 80% throttle for extended time in the same flight. This will help to keep your batteries from getting warm (think fire…think explosion) and in flying a little more conservatively you’ll be adding to the battery’s lifespan.
If your plane has an automatic cut-off for low voltage, try to anticipate it and land on your own before it kicks in. One “do not fly without” thing to ensure you have installed on all your electric planes is a BEC battery eliminator circuit. With the BEC your servos can still get power in the event that there is not enough juice left in the battery for your motor.
Disposing of LiPo Batteries
Inevitably, you’re going to crash your plane or puncture a battery pack or just reach the end of the pack’s lifespan. You’ll need to know proper LiPo battery disposal techniques.
- If the battery or battery pack has been damaged or is leaking, the safest method of disposal is to completely cover the battery with salt water. Use about a quarter cup of salt for every liter of water and let the battery soak in this solution for at least two weeks.
- If your battery has not been damaged, you will first need to discharge it completely (or as close to that as you can get). Then, proceed to use the salt water method described above. After your battery or battery pack has soaked for two weeks, take the battery out, wrap it in something to cover it and throw it out with your regular trash.
- If you live in a rural area, incineration of LiPo batteries is not recommended.
Using LiPo batteries will only add to the pleasure you take in getting outside with your plane and taking to the skies. LiPos are light weight, have a fast discharge rate (so even the most powerful motors don’t lag with them) and longevity to argue in their favor. A LiPo battery is clearly the best choice available for your RC plane.