I have used many liPo batteries with my drones and other RCs over the years and have had a few of them puff up. What are the main reasons that LiPo batteries puff up? And are there ways to avoid LiPo batteries getting like this?
All LiPo batteries face a process called electrolyte decomposition. This means that all LiPo batteries will produce oxygen, some carbon dioxide, and some carbon monoxide through normal use. This process, however, is greatly sped up when certain things happen to a LiPo.
These are the things that will cause noticeable "puffiness" in LiPo batteries:
- Over-Discharge. Don't let a LiPo go below the minimum safe voltage (Example: if you fly your drone too long and the battery gets below ~3.3v per cell) and don't pull too much current from the LiPo. (Example: using a low C-rating LiPo, like 20c, on a high performance race drone.) Make sure you pay attention to battery voltage when flying and make sure you have suitable C-rating.
- Overheat. Exposure to heat can cause battery puffiness. Make sure to let LiPo batteries cool off before charging and don't fly when it is too hot. Also, make sure to store LiPos in a cool location.
- Overcharging. If a LiPo is charged higher than 4.2v per cell, it can cause puffiness. Make sure you use a good balance charger to avoid this.
- Improper storage. Storing LiPos at full capacity is a major cause of puffiness. Make sure to storage charge LiPos before putting them away for any significant time. If you have a good charger, storage charge is one of the options. Also make sure to store LiPos in a cool/cold area.
More in-depth information here.