5s lipo or 6s2p A123 ftw
ON another note, yeah, I hope there were two of those Zippies in parallel, as 3500mah x 30c = 105amps at best, and as much as I like the Zippies, I prefer lipos that can do 120amps plus, hence why I use a pair of 5s 25-35c 4000mah zippy-Hs in parallel to get me 200amps continuous for my hefty setup (lots of hard braking and violent acceleration and no dead esc yet).