My cummins onan generator is using oil at an alarming rate and I want to wait till the off season to replace it. I have a 2000 watt inverter generator but it's a 120v. Is there a way to run this generator just to power my battery charger, and 120v appliances? I'm not sure how that works with the 240v system on the boat. It's a 1980 50 convertible.