Adding a Second Battery, need suggestions on wiring the ebay

[1970Maverick]

It would be a wise thing to put a fuse on each end of the positive cable in case the cable ever gets shorted to the frame. Otherwise you could end up doing some unplanned welding. Remember a battery is an unlimited source of current, it has no internal cut off. If it's shorted it will continue to supply current until the wire melts or battery explodes. It's not the voltage but the current that needs to be considered.

 

[5280tunage]

Agreed. I generally use marine grade breakers on both sides. I know that some people run wires alongside and even in many places inside the frame. You can us a fish tape to help pull through the frame rails, but 1/0 might be a bit tougher. I would definitely agree with the recommendation of wrapping it with loom the whole way. Here's an interesting question though. I know that I've read multiple articles on doing A/V work on these Fords, and a lot of folks describe various ground issues with the aluminum body, so many run grounds all the way back too, but if not, at least do some serious ground work, like grinding/surface prep, etc. Maybe even testing voltage drop etc. Are you thinking of using something like a good deep cycle? I know you mentioned LiIon, but i'd be wary of quality there, and the possibility of overcharge and fires.