A few thoughts.
You have the house batteries wired in parallel. I think this is a good approach. This makes the 2 batteries function as one and that should provide more useable energy and longer life for the batteries.
You're right. It's the only way to wire a multi-battery bank. Unless your goal is to take two 24V in series to achieve a 48V bank. But even then, that now single 48V bank should be wired parallel into the electrical system.
I would like say this regarding batteries and my thinking. I'm not using "start" battery for my second bank. To me it's a reserve battery, working with a off-1 scenario - reserve is just that, reserve.
I would suggest a few modest changes.
1 - Eliminate the positive feed from the charger to the start battery.
The ProNautic charger charges the two banks independently. What would be the advantage of an ACR over using the charger's multi-bank functionality?
2 - Eliminate the positive feed from the start battery to the house panel volt meter.
Yes, no - I could go either way with this one. The charger's front panel, or a remote battery monitor would give me the same information.
3 - Add a SPST battery switch between the Start Battery and the Battery Select Switch
You have a suggestion? Other than those knife switches, I really haven't found a suitable surface mount switch.
4 - Fuse the Start battery with a
battery terminal fuse at 250 amps.
Right, so noted and added to the design. However, if I'm using bank one as primary operational bank, running the house and starting the engine, would a 250 amp fuse be used there?
5 - Change the 1-2-both battery switch to a
Blue Sea Dual Circuit Plus switch.
I've down loaded the instructions for the M-series Dual Circuit Plus, and they're about as help as - well not much. My feeling is this involves your suggestions of 1 and 6. With the functionality of the charger and that my current 1-both-2 switch acts as a selector and combiner; what are the advantages and disavantages?
6 - Add an ACR between the DC Positive busbar and the positive terminal on the start battery with appropriate fusing.
See responses 1 and 5.
7 - Add a
battery terminal fuse on the house battery
Just as with the reserve battery, yes. As I asked though in response 4, 250 amps required here?
8 - Add a battery switch between the house battery and the positive bus bar.
See response 3.
I think that's it.