I killed a finedesign 4s 3700mah firefox pack running a 7xl nemesis. Cris sold me the combo telling me it would work fine and that if it did not he would gladly warrentee the pack or the motor...well he was wrong the 7xl was way to hot for the cheap 20c pack and it got to hot. He went back on his word and would not warrenty the pack...my loss.