Battery bank hook up?
 

I have 2 502 engines in my boat. I have two batteries for starting ( one for each engine), 2 batteries for stereo and 2 batteries for house 12 volt power. how do I wire all batteries to charge off of the 2 alternators. ( I have one two bank charger for the stereo batt's and one for the house batt's. I need to be able to charge all banks off of the engine

The port engine charges the starting batt and one of the stereo batt.

The starboard engine charges its starting batt and the other stereo batt.

When I have the stereo on while parked I switch the batt selector to 2 on both engines, then to 1 when I start the boat and to both when running.

Right now the house bank is only charged from the on board charger, I would like to be able to start the boat to help charge these when I am on the water away from shore power.

you need a battery Isolator ...best way would be to have a setup where either motor will charge all the batteries ...there are Isolators than have input from 2 Altenators and then output to 3 Banks ....It sounds like your stereo and house bank batteries are parallel ... so to the Isolator will only see 3 batteries ... you might need 2 Isolators ...
Port motor would charge
1) port motor battery 2) Star motor battery 3) house Bank

Starboard motor would charge
1) Starboard Motor Battery 2) Port Motor Battery 3) Stereo Bank

http://www.emarineinc.com/products/a...isolators.html