Originally Posted by ckearns

Take all the +12v and combine them into a single output and use as many black/common wires as you have +12v wires into a large common return.

Hook a charger or two up to it and get to charging! You may want to tinker with the amperage rates until you find the point where the PS shuts down from amperage overload protection and keep it lower than that when you're at the track.

A tire truer (12v) or comm lathe (5v) will most likely draw too many start up amps (12A and 15A limits respectively for yours) and cause the PS to shut down, even if it's the only thing on the PS at the time. In my mind, this makes the 5v rail pretty much useless and you can cut or pull all those wires off right at the circuit board. I'd love to have a 5v rail for running a comm lathe, but that proposition is not looking so hot from the power supplies I've cut up.

You may be able to find a 600w+ PS that can handle the startup load if they're running a single rail at 25-30A. I don't have one that big laying about or I'd chop up the harness and run the experiment myself.

Chris