Turnigy LiPo dud confirmation

Finally got my board running and unfortunately wasted one of my LiPo batteries in the process. I’m using 2 Turnigy 5000mAh 5S 20C Packs connected in series to a VESC. When I started the ride, both packs were brand new at about 20V each with no more than a 0.02V difference between each cell. After a little test riding, the board finally shutdown at 30V (which looking back was probably way too low, especially for testing). Excited/nervous to charge Lipos for the first time, I saw that one of them caught a case of the puffs. The dud had dropped to 12V (2.4V/cell) while the good battery was still over 18V.

Is this just a case of a bad LiPo (from reading @onloop it does not seem to be uncommon) and not an issue with the VESC regen that I need to figure out? I had it set to the default, motor min -60A and batt min -20A.

Here’s how I connected the batteries just to make sure I didn’t have a brain fart on something so trivial

The puffy battery also did start off about 2mm thicker than the good one when it arrived brand new, so that is sort of why I jumped to the conclusion that it was the battery’s fault and not mine. Anyway, just though I’d ask now before I burn through some more crappy/cheap hobbyking batteries.

Well you just smoked out your lipo i guess. Over draining them to the end. Lipo needs to get recharged when they are 3.2V - 3.4V left. If you drain them below 3.0V then you might just finished that lipo life / cut down the lifecycle significantly.

The connection is ok, thats correct for setting it in series for getting 10s.

Lipos are always a guessing game next time when receiving batteries perform a proper inspection before using them. This should have been a red flag.

And this batteries for the 1-3 uses need to keep the load low in order to break them in.

One more thing, Get rid of that pack, is too much of a fire hazard in you living place.

Yea I have it outside on some bricks by itself in a metal trashcan until I figure out what to do with it/where to dispose of it. I’ve see videos of what happens when a cell phone lipo burst so I’m guessing the 5 cell going up in flames wouldn’t be pretty.

Thanks for the tip though, I’ll be sure to go easy on the next pack to start off.