the MaH and voltage have nothing to do with eachother, mAh is milliamper hour, a measure of the current. voltage is the battery's power. so you could use a 1500 mAh battery without problem, but a 1500V battery will set your motor on fire.
most airsoft guns use 7 or 8 cell batteries, usually called 8.4V or 9.6V respectively. most can handle a 9.6v 3300 mAh battery without issue.
Last edited by durak; March 12th, 2012 at 12:09..