my mini max battery for my 18T prolly lasts 20-25 minutes with the small tires on at 2.0amps. That has prolly had about 30 chareges tru it. My race batts for my MRS4 are 1100 saddle pack, which are at 1.9a for 5 minute heats, and at 1.5 for 8 minute mains. Prolly has about 15-20 charges through it.