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Why Do RC LiPo Batteries Puff Up?

If you use LiPo batteries in your RC car, truck, or drone it’s likely that you will encounter a swollen or puffy battery sooner or later. When you have a LiPo battery that has started to swell you’re definitely going to start wondering what exactly you can do to make that better or what you should do next. 

For starters, you’re very likely going to be wondering why your LiPo battery is puffed up in the first place. 

A LiPo battery will begin to puff up and swell because of the gas generated by normal use of the battery. When a LiPo battery begins to swell it is a sign that your battery is at the end of its life and needs to be replaced. 

Some people say that letting it cool down will fix the issue and while that might be true temporarily if you don’t replace the puffed up LiPo you are at risk of having a fire or explosion while using your RC car!!! 

At the first sign of swelling or puffing you should stop using that battery IMMEDIATELY and you should remove and dispose of it. LiPo batteries are not extremely expensive so replacing it won’t break the bank but if it catches your RC car on fire or worse your house you will be out of a lot more money!! 

LiPo batteries can be found at a variety of places locally or even online at Amazon. You can find some of the best sellers on Amazon by clicking here.

If you want to see what happens when a LiPo puffs up and is not replaced check out the video below. It is about the 30 second mark when you can see the dangers of swollen LiPos. 

HYPER GO H16DR 1:16 Scale Ready to Run 4X4 Fast Remote Control Car, High Speed Big Jump RC Monster Truck, Off Road RC Cars, 4WD All Terrain RTR RC Truck with 2 LiPo Batteries for Boys and Adults

A good RC car doesn’t have to cost a fortune. This 1/16 scale model is 4WD and can reach a top speed of almost 30 MPH!

With speeds like that and 4WD you can take this RC car almost anywhere!

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What Causes LiPo Batteries to Puff Up?

It’s very normal for gas to be generated in a Lithium-ion battery. Even when your battery is not abused, merely using your battery every day will naturally generate gas by a process known as electrolyte decomposition. If you overheat or over-discharge your battery, the process of electrolyte decomposition happens even faster.

What is electrolyte decomposition?

A LiPo battery is composed of three things: the anode, the cathode, and the electrolyte. The anode and the cathode are the positive and negative terminals of the battery. The electrolyte, on the other hand, is a chemical inside the battery that ensures that charged ions can travel from the anode to the cathode in the discharge process and from the cathode to the anode in the charging process.

Electrolyte decomposition occurs as the electrolyte breaks down chemically. In a LiPo battery, therefore, as the electrolyte breaks down, what you have at the end is lithium and oxygen. Depending on whether you are charging or discharging your battery, this makes lithium oxide on the anode and cathode.

But, you are also going to end up with a lot of extra oxygen that does not adhere to the cathode or anode. This excess oxygen is one of the reasons the battery will swell up when it is wearing out. 

Are swollen batteries dangerous? 

Now, the next question you’re probably going to be asking is if swollen batteries are dangerous. If the video above didn’t answer the question (or you didn’t watch it) the answer is most definitely a yes. 

Swollen batteries are extremely dangerous as a matter of fact. Many puffed up batteries have started a fire in a number of instances, so you want to be very careful with any battery that has started to swell up. 

Now, that doesn’t mean that every single puffed up battery will explode into a fire the moment you use it, but it actually means that a very high percentage of them are very dangerous. It’s not worth it to take the risk which is why you should stop using the battery immediately and replace it. 

What can you do to fix a swollen LiPo battery? 

Many people feel like there should be something that you can do to fix these batteries when they swell up, but is there? 

There’s nothing that you can do to fix a swollen LiPo, and there’s nothing that you should try either. Trying to fix a swollen LiPo battery is going to put you at such a high risk of hurting yourself or starting a fire it’s not something that anyone should ever even try. 

It’s really not worth it to burn your house down or get yourself injured just because you want to save a tiny bit of money by getting a couple of extra uses out of the battery. 

When your LiPo battery gets swollen, the ideal thing for you to do is dispose of the battery properly and purchase a new one. 

How to Dispose of Puffed up Lipo Batteries

The ideal way to dispose of a swollen LiPo is as much the same as the ideal way to get rid of any old or no-longer-serving battery. You need to first completely discharge the battery.

There are two main methods of discharging a battery that people use; hooking it up to a light bulb or to putting it in a bucket of saltwater.

If you are going to use the light bulb method, it is ideal to use the 12V, 20 Watt halogen bulbs. These bulbs are easy to solder to so it is a lot easier to attach lead wires and connectors. This, in turn, makes it very simple to just plug in your battery and allow it to discharge. You can hook multiple in parallel so that you can get the discharge rate you want.

When you have totally discharged your battery, go to your nearest battery recycling drop-off point and drop it there. Be sure to call ahead and find out if they accept damaged batteries.

The salt water method is not preferred as it can be dangerous as well so I would not recommend using this method if you can avoid it. If you have no other choice then you basically put salt and water in a bucket and submerge the battery to discharge it. 

What to Do to Avoid a Swollen Battery

LiPo batteries will almost always swell up when they reach the end of their useful life. However there are some things that you can do to make sure that your LiPo batteries don’t swell up prematurely. 

Here are some things that you can do to make sure your battery does not swell up early. 

Charge properly: Ensuring that you use a quality charger to properly charge your battery is a great way to ensure that it doesn’t swell up before it has reached the end of its life. To ensure safety, put your battery in a LiPo bag when you’re charging, and if you do not already have a LiPo bag, try to get one as soon as possible. 

With a LiPo bag, you minimize the chances of anything going wrong, and if anything goes wrong, it is, at least, contained.

Don’t over-discharge: Ensure that you have stopped using your battery before the voltage reaches the minimum cut-off voltage. Most modern RC vehicles will have a setting that prevents over discharging but you have to make sure that it is turned on. 

Be cautious of heat: Avoid using or charging batteries when they are warm. When you are done using them, let them have some time time to cool off before you charge them. When you are done charging them, let them rest for a little while before you use them as well. 

Store properly: Make sure that you don’t store your batteries in a hot place. If it’s the summer, for example, avoid keeping them in your car’s trunk and also make sure that your LiPo batteries are stored at the proper storage voltage. Storing your LiPo battery in a wrong location very significantly increases the risk of swelling, so you really want to avoid that.


Generally, one thing you should keep in mind is that if LiPos are used wrongly, or even as they age, gases will begin to form in the batteries, and the result of this is swelling. The moment you notice that your LiPo battery is puffed up or swollen, the first and most important thing for you to do is to discharge it completely and get rid of it in the proper way. 

Don’t try to fix a swollen LiPo battery because you might be putting yourself and your property at a high risk of getting injured or damaged. 

Also, keep in mind that the best place to get advice on a swollen LiPo battery is from your local hobby shop. As a matter of fact, it might be best to take the swollen battery there and let them discharge and dispose of it for you if they offer that service.