battery set up and possibly adding a third battery?

duane.mosley

i have been reading but not finding what i need to know,  so i thought i would start a new topic. i just purchased an '06 250 express cruiser,5.7 volvo penta.  the battery switch has 4 positions,  off, 1,2, or combined(emergency start). does this style switch, which seems to be factory, stay in position 1  at all times? does it charge the house battery in position 1?  another question while on topic, can i add a second house battery, wired parallel, without changing the  isolator? thanks in advance for any assistance

212rowboat

about the second house battery down wind of the isolator and present one:  yes, you can run an additional battery there, but, you'll want it to be the same capactiy and discharge rate as the existing house battery- easiest to go with the same make and model to make sure.... and... you'll want them to be as close to duplicate in condition as well... the way you make certain?  Buy two new duplicate batteries and wire them in. parallel and be happy. 

howardrams

And yes, it should be that both starting batteries and house get charged by alternator when the engine is running, and they both get charged whether you are in 1 or combined.