Battery choice should be determined by the motor
Your motor will have a continuous current rating
Example
100 Amp motor
Pack 1 - 5000mah 20c pack = capable of delivering 100 amps
Pack 2 - 5000mah 40c pack = capable of delivering 200 amps
Pack 2 is a better choice as 1 is close to its limit
Generally speaking higher mah = longer runtime as long as the packs can keep up with the motor
Cheers
Last edited by crusey_aus; 03-22-2011 at 05:49 AM.