I am only ten years old. I am trying to build a robot, but my battery is too heavy and my motors are too weak. I am using a R/C sabertooth and I need 6 volts at least to run it. I have tried AA, lithium, and Ni Cad, but each has it's own problem. I am low on money and I need something around thirty bucks. The price can go higher a bit like ten bucks, but the battery needs to be much less than a pound so the robot can move.