Originally Posted by
BaconRaygun
This is gonna sound really wrong to some people, but there's a ton of proof to back this up. Charging LiPo's is an endothermic reaction, so charging a warm LiPo actually has a cooling effect. If there is an internal short, a high charge current can make the pack go boom, but that's a different conversation.
There is nothing wrong with charging a warm LiPo. The problem lies with discharging a warm LiPo.
Every single battery I've charged warms up when charging. I'm pretty sure the resistive losses due to current flow outweighs any endothermic reaction. YMMV depending on your charge rate.