We run a Pro-Lite in our car. Weighs 9lbs and spins the 14.1 738 over like it has no plugs in it.

A friend of ours uses remote control, toy helicopter batteries. He has 4 of those wired in series that run his entire car. With the (4) bundled together, the "pack" is about 6x6" and approx 10" long, weighs a couple pounds. The car has a twin turbo big block and all the associated paraphernalia to go with it. At a recent race, the full size Kenworth, that he uses had a dead battery. The helicopter battery pack started the KW.

Battery technology has come a LONG way

Monte