LiPo Battery Care – Knowing How To
LiPo batteries offer plenty of power and run time for any radio control enthusiast. But that power and runtime come at a price. When it comes to taking care of your battery, Proper LiPo Battery Care is very important! LiPo batteries are capable of catching fire if not used properly – they are much more delicate than the older NiMH/NiCd batteries. The problem comes from the chemistry of the battery itself.
Lithium-Polymer batteries contain Lithium. Lithium is an alkali metal, meaning it reacts with water and combusts. Lithium also combusts when reacting with oxygen, but only when heated. The process of using the battery, Sometimes in extreme ways that we do in the R/C world, causes there to be excess atoms of Oxygen and excess atoms of Lithium on either end whether it be in the cathode or anode of the battery.
This can and does cause Lithium Oxide to build upon the anode or cathode. Lithium Oxide is basically corrosion, albeit of the lithium kind, not iron oxide, which is otherwise known as “rust”. The Li2O causes the internal resistance of the battery to increase. Internal resistance is best described as the measure of opposition that a circuit presents to the pathway of power.
Some modern chargers have the ability to read the internal resistance of the battery in milli-ohms. If you have one of these chargers, you can get a sense of how your LiPos are performing and how the internal resistance of the battery increases as they age. Keep track of the internal resistance reading each time you charge your battery and record the increase over time. You will see how the process of just using the LiPo battery begins to wear it out.
Keep Battery Cool – Low Temp
Heat causes the excess oxygen to build up more and more. Eventually, the LiPo pack begins to swell. This is due to the oxygen gas build up inside the battery. This is a good time to stop using the battery. The battery is telling you that it has come to the end of its life. Further, use can and will, be dangerous.
After the pack has swollen, continued use can cause even more heat to be generated. When this happens, a process called Thermal Runaway occurs. With proper Lipo Battery Care, this can be kept to a minimal or non-existent issue.
Thermal Runaway is a self-sustaining reaction that is accelerated by increased temperature and in turn, releasing energy that further increases temperature. When this reaction starts, it creates heat. This heat leads to a product that increases resistance Lithium oxide(Li2O), which causes more heat, and the process continues until the battery busts open from the pressure. When this happens, the combination of heat, oxygen, and the humidity in the air all react with the lithium, resulting in a very hot and dangerous fire.
However, even if you stop using the battery when it swells, you still have to render it safe. If you puncture a LiPo that has swollen and still has a charge, it can still catch fire. This is because the unstable bonds that exist in a charged battery are in search of a more stable state of existence. That’s how a battery works, you destroy a stable chemical bond to create an unstable chemical bond. Unstable bonds are more apt to release their energy in the pursuit of a more stable bond. This is how we get power from the battery.
Proper Care & Storage
Back in the early days of RC’s we could run your Vehicles battery dead and put it up, Not worrying about it till next time we run to charge them up and go out. With today’s LiPo batteries this should not be done. LiPo batteries should not be stored with a full charge when not in use and should be stored at room temperature.
What I recommend is to put your LiPo batteries in storage mode after every run. The ideal storage voltage is 3.7v per cell, Which is the nominal voltage of each cell. This isn’t necessary if they are run daily, but it does build good habit if you storage charges them after every use. When you do it every time, It becomes a habit and you don’t have to worry about if you remembered to put it in storage.
I have had many people come to me with batteries that died prematurely because they charged it up, intending to use it, but life got in the way and they never remembered to put it back to storage voltage.
Honestly, I am guilty of this myself! I don’t know how many times after a run, I would throw my batteries on the charger and charge them up a full charge. Then after they are fully charged they sit for a couple days or even a week sometimes and never get put to storage mode. I have lost 3 of my batteries due to this.
Important – Storage Charge Your Lipos
Lithium-Polymer batteries can be damaged by sitting fully charged for as little as a week. This doesn’t mean they will get damaged every time you leave them for over a week. It just means they can and as I have mentioned, I’ve seen it happen. So don’t forget to put your LiPos at storage voltage when you’re done using them.
They should also be stored in a fireproof container of some sort. Most people tend to like leaving their LiPo’s in a LiPo bag, as they are portable and protect your workshop from catching fire should the LiPo combust. I have also seen people use empty ammo boxes, fireproof safes, and ceramic flower pots. Whatever you have or can buy that will prevent any fire from spreading will be worth it in the unlikely event that anything should happen. This is the reason LiPo Battery Care is so important with today’s LiPos. For information on some great battery chargers go here!
The most common problem people have with LiPo Batteries is a result of improper storage! With proper care, these problems can be avoided!
LiPo Battery Disposal
When a LiPo battery goes bad or becomes unusable, No one really wants to keep them lying around. This is due to being the fire hazards that they are and they are not usable anymore so why keep them around.
Do you have a bad LiPo battery? Do you know what the process is to get rid of a bad LiPo battery safely? Not sure what to do with it? Well, I will give you these answers.
Before disposing of your LiPo battery, You may want to be sure the warranty has expired. Some companies have one-year replacement warranties that you may be able to take advantage of. Now, if you perform the following steps before seeking a warranty replacement they most likely will not help you, As most warranties will be voided if you do any of these steps below.
- Discharge the LiPo battery as far down as you safely can. You can do this a number of ways. Most computerized LiPo chargers have a discharge feature in them. If you don’t have a charger with a discharge feature, you can run down the battery in your vehicle – keep in mind that you risk a fire and potentially damaging your vehicle doing this, so take care to have the necessary safety equipment around. Alternatively, you can build your own discharge rig with a taillight bulb and some wire. Simply solder a male connector of your choosing to the tabs on a taillight bulb, and plug the battery in. Make sure to have the battery in a fireproof container while doing this.
- Place the LiPo in a salt water bath. Mix table salt into some warm (not hot) water. Keep adding salt until it will no longer dissolve in the water. Ensure that the wires are all entirely submerged. The salt water is very conductive, and it will essentially short out the battery, further discharging it. Leave the battery in the salt water bath for at least 24 hours.
- Check the voltage of the LiPo. If the voltage of the battery is 0.0V, great! Move onto the next step. Otherwise, put it back in the salt water bath for another 24 hours. Continue doing this until the battery reaches 0.0V.
- Dispose of the battery in the trash. That’s right – unlike NiMH and NiCd batteries, LiPos are not hazardous to the environment. They can be thrown in the garbage with no problem.
What if you don’t feel like going through this process yourself? Check with your local hobby shop, They will most likely have a service that will allow you to take in your old batteries. For those of you in my area, You can bring the battery into me and I will dispose of it for you at no cost. If you’re not in my area, The best thing to do is contact your local hobby shop to see if they offer a similar service. If your looking for LiPo batteries click here.
Now, that you have the rundown of LiPo Battery Care, Do you feel you have a better grasp on how to care for your LiPos? What do you think of this article? Please leave your thoughts or opinions in the comments’ area!