1991 Wellcraft St Tropez 3300. House Battery Bank

[SilveryMoon]

We just purchased an 1991 wellcraft st tropez. TWin 350 inboards. There are only 2 starting batteries and I would like to add a house bank of batteries.
There is an electric panel under the stairs going into the cabin with a battery select switch, off, battery 1, both, battery 2.
There is a location in this panel to install a second switch.
Is there a wiring diagram available that will help me ensure I add the house bank correctly.

20210506_121848.jpg

Any help would be appreciated.
Thank you

[Billm]

Why go to all that trouble? A quality group 24 deep cycle battery will start those inboards just fine. Always select one battery or the other never both. Is that hourmeter for a generator? Then your generator can recharge the battery not in use.

[SilveryMoon]

The meter is for the engine hours. We spend our summer on the boat staying at anchor for several days at a time. We are adding solar panels and a house bank so that we can do that. We have done the same on our previous boats.
I was actually surprised that this boat did not have a house bank to start with.
We do not have a generator.

[CptBill]

First I'll say this, if it where me I'd add a generator instead if more battery's. Now you can add and another batt. switch but the problem is going to be how to charge all these battery's. 1 engine charges 1 battery at a time also adding or replacing a battery charger then there's the solar charger. Boat US or the ABYC web sites should have all the requirements for adding battery's and all the switches and other stuff your going to need. Today line of generators are very quiet and fuel efficient

[Billm]

Got it. That long foredeck will be ideal for solar cells. You never feel claustrophobic in the boat, even in the rain.