Just completed an upgrade to my 1994 Carver 370 Aft Cabin to add a small "house" bank of batteries. Boat originally came with start batteries for each engine + generator. However it was configured such that both engines started and ran on whichever battery was selected from the master switch. This also meant that both alternators were shorted together - really bad if on fails, the other is also not long for this world. Anyway... got into the bilge and re-positioned the existing batteries toward the bow to make room for a pair of group 27 deep cycle batteries. Swapped the master switch for a dual switch: (https://www.bluesea.com/products/6011/m ... itch_-_Red). Now start batteries for port and starboard just go to each engine. I added a Promarine battery isolator (ProIsoCharge130 2•4) to isolate / combine outputs or each alternator. This unit monitors up to 4 battery banks and directs charge to lowest bank (after topping off 1st start battery). On my boat there was a single pole switch to turn off battery to the generator. I left this one in place with a second dual switch with house and generator battery routed there first. Both these switches have to on to juice the generator. This new set-up allows me to turn off all banks with just house bank working. Should note that house power to breaker panel is normally connected to the main battery switch. The input to the two 50A breakers must now come from the house bank switch. System is finally installed and seems to be working flawlessly. Must give a shout out to Lucas Landry with Promariner for helping translate / interpret the installation instruction (manual is not great). Longer term plan is to route the house bank to a small 2000-2500W inverter to allow the coffeepot to run without starting the generator. I'm an old sailboater and am used to spending days on the hook without generator or running the engine (small electrical footprint). Of course the motor yacht does not ventilate as well as my old Hunter 36 sail boat so we will see if I can live without AC in North AL. Attached is a .jpg file showing the new battery configuration. Also added a remote battery watering system since the batteries are a major PITA to access for checking electrolyte levels. Know that I only have ~100 AH of house capacity (drawing less than 50%) but now that infrastructure is in place adding additional batteries is straight forwards once I make some mounting provisions.