My son Adam has a 1988 EZGO electric golf cart that he bought for 50 bucks. Over the last couple of months we went through the cart and changed all the wires, the pot box and the forward and reverse switch and new solenoid. We got up to the campground today and he tells me the golf cart quits running at full throttle. I once heard that the pot box causes this. We replaced the pot box with a new one. The batteries are good and read 6 volts. Can a dead battery cause this? Thanks for the help.