Yeah, it seems to be high current spikes that kill them; I had a few puff up when Big Bully stalled a motor and blow an ESC, and the rest died when I was using them while load testing my new ESCs. In Nuts for Season 1 I designed for 3 packs in parallel, 2 in series to give 12.6AH at 8S. This was to get the current required to run the electric lifter mech as well as the drive. Once the lifter mech was removed I dropped it to 2 packs in parallel (8.4Ah).