I considered using one of those on my rig, but was worried about the pack bending and then failing - apparently LiPo batteries can catch fire/explode if they get damaged internally (through bending or being pierced). That's why I picked a battery in a hard metal cylinder with built-in protection circuitry - hopefully much more likely to survive my flying style without setting fire to my kite
Damaged battey pack setting a kite on fire?
Bad for the kite, but what a great video.
