Well, if you are a retired EE, then you obviously have the knowledge to sort it out.
But in my experience tracing wires on a 34T is a difficult job, particularly the smaller gauge stuff. But the 2/0 stuff is fairly easy to follow.
Anyway, for what it is worth, this is how my 34T single was wired:
There were three battery banks: bow thruster, bank 1 and bank 2. I did not have a genset.
The output of the alternator was wired through an isolator. One output went to the bow thruster battery and the other went to the heavy starter lug. The heavy starter lug was wired to the common terminal of the 1,2,both switch. Each battery bank was wired to the 1 or 2 terminal respectively of that switch.
One of the banks supplied power directly to the panel inside the stair opening. This panel is meant to be powered all of the time: it runs bilge pumps, etc and that is why it wasn't wired through the switch which could be turned off which wouldn't be good for bilge pumps.
The common terminal of the 1,2,both switch supplied power to the starter and to all of the house loads (the ones served by the panel inside the cabin).
I set up bank 1 as the starting bank and used the factory supplied 4D for that. I set up bank 2 with 4 golf cart batteries wired in series/parallel. So at anchor I switched to bank 2 to power the house loads and to save the starting bank. I would switch back to 1 to start the engine and then to both to charge them both.
It worked reasonably well. I thought about installing a combiner which would have made the switching automatic, but laziness and a fair amount of rewiring required to make it right, got the better of me.
None of which is to say that your twin is wired the same way.
Good luck sorting it out.
David
