I wouldn't go anywhere below 6500mAh on a battery and make sure you get a decent pack with lower internal resistance. Don't run the packs any longer than you would race. This class more than any other is HARD on batteries. If you run them down to lipo cut off as hard as these trucks can pull your packs aren't going to last very long. The Vant 7600 my son just got is a great pack for a good price.