inverter/batteries etc.

I have a 2006 mainship 34 with a 3000wt inverter powered by 2 series 31 batteries. I also have 2 8d batteries for starting the mains and house power. How can I tell if the 8d batteries are both starting and house power are is one 8d for starting and one 8d for house power. Also if there a way for me to use the inverter to charge one or both of the 8d batteries? I have no gen, the boat never had one, so I have no to way to charge the 8d batteries other than the alternators or shore power unless I can do it with the inverter. Help!

I think you need to hire a marine electrician to figure it out for you. Or read Nigel Calder's Mechanical and Electrical Manual and then ask your question again if you need further help.



David

You are going to have to crawl and dig around and follow/test the wires. Eventually you will want/need to map your electrical system, but a quick and easy way to answer your question is to disconnect one 8D battery and then see what does and doesn't work. Repeat with the other 8D battery. Of course even this doesn't tell you the whole story as you may have battery switches that allow you to change around your configurations. Using a battery powered inverter to charge other batteries is not a good plan. Your only good options to charge, beyond what you already have, are solar panels or a generator.

jsplichal2 said:

...but a quick and easy way to answer your question is to disconnect one 8D battery and then see what does and doesn't work. Repeat with the other 8D battery. Using a battery powered inverter to charge other batteries is not a good plan. Your only good options to charge, beyond what you already have, are solar panels or a generator.

Click to expand...

Adding to that...

Or maybe there are battery switches for ON and OFF, perhaps slightly easier than a physical disconnect.

A common installation from Luhrs Group boats (including Mainship) might have one battery bank for each engine -- and each of those batteries may also do double duty as house battery for approximately half of the hotel loads.

If there's a switch, turn OFF one battery (or disconnect if necessary) and see if one engine won't start, see if half of the house -- maybe one side of the DC panel -- also doesn't work. If so, try the other one, to confirm.

Might be a PO installed the inverter to service very light AC loads, given that 2x G31 batteries isn't all that much capacity in the grand scheme of things.

Good to have mentioned that inverters don't usually charge batteries... from other batteries. I'll add there are inverter/chargers -- but it doesn't sound like that's what OP has.

-Chris