[RyanN]

I've had good luck with the marine battery selector switches. We have one on our 20' Boston Whaler that works good, and I decided to put on on our T-Shirt Shooting robot, and I can switch batteries without cutting the power at all. You have the choice of running 1, All, or 2, as well as an off position. Diodes are great and all, but for the current that you are running, I have trouble seeing diodes supplying that current without getting hot. The battery switch stays cool and transfers a lot of current (I think ours is rated at like 120AMPS continuous, 200 < 30 seconds, 300 < 10 seconds or something like that...