Bullfrog runs on 5S packs, 2 in series to get 33V 2 parallel to have 8400mAh.

2 years in use, and yes, swollen a bit. The LiPo testers we have all say "still in great shape".

Shock mounting is very important tough.

Tough As Nails runs on 4 5S 5000mAh Turnegy nanotech packs. 2 series 2 parallel delivering 37V 10ah. But after 2 events it's not really clear if it's the right way to go.