[Drew]

To answer this question to the best of my knowledge I would have to say that the battery would be mounted to an unmovable peice of your robot. Not because it says this anywhere in the rules but because if the battery holder moves then you run a chance of it falling out or wires being hit or disconnected. If the platform that it is mounted to does a complete 360 then you must make sure that the wires can handle the spinning so that you do not rip them from the plug. This is just my input on this situation. Also you may want the battery closest to the ground and opposite of your arm mechanism to maintain stablility of the robot. not a constand changing of weight.