heh. we were writing at the same time.
IMO, you don't want the battery charging at anything more than 30 amps, and even that for less than a minute. 5 amps or less. So I guess what I'm saying is the ammeter range needed depends on how the battery(s) will be used and charged. If it, or they will be getting deep cycled and put through heavy load, probably need a regulated charge and maybe one of the leece neville alternators.
With all the power distribution inside, as you drew, an internally shunted ammeter could work. The question is whether the ammeter and everything else in that line would stay cool enough when running on battery alone, and then again when recharging. It still might be good to have a dedicated charging wire on the engine compartment side - and use a external shunt for the ammeter.
