Can I run a 120v generator to the 120 side of my 50 hatteras?

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.

Yes but a bad idea. Its dangerous and not a good solution except for an emergency.

I realize that simple yes and no answers are most welcome, but a couple of alternative thoughts to a gasoline generator running on board, somewhere.

Have you considered an electronic inverter (Magnum, Victron, Xantrex) attached to your house batteries. Keep one main engine start battery isolated so you can always get going. If you are so inclined, keep the inverter generator as a backup, but do not use it without constant monitoring. When underway, your main engine alternators will charge the batteries. At the dock all power will come from shore power as usual.

Have you considered just calculating the oil use rate of the generator and feeding it on a makeup schedule, without interruption.

My opinion, the gasoline inverter generator is absolutely the last choice.

I agree with the two gentlemen above.

I have been checking and filling on a regular basis. But the consumption has gotten to 1\2 gallon every 8 hours of use and it's starting to smoke. I want to rebuild it before it comes apart. I have a 2 week trip coming up August first and am looking for a temporary solution. I do plan an invertor again over this winter's refit as I just got her in April. The first week I'll be at the dock in Martha's vineyard, but week 2 I'll be in the hook at block island, and I will need the generator.

Setting all other concerns aside, the basic question of would a 2K inverter attached to the 50 amp/125 volt inlet on the boat function, my recommendation is to try it. Just for consideration is a quick look at what you will be attempting. The 125 volt/50 amp inlet attaches directly to an isolation transformer that provides ground isolation, boost to a 125/250 volt output and, places a sizable inductive load on the inverter output. Inverter generators are rated for resistive loads, and the design of these light units use high frequency designs versus line frequency designs. High frequency inverters do not handle inductive loads well.

My opinion is the setup is more likely to not function due to the very large inductive load being placed on the inverter output of the external generator/inverter.

If you decide to try it, just be sure that someone that fully appreciates marine electrical characteristics and hazards is directing the experiment.

Carbon monoxide is a real issue. Portable generators dont vent well.

Frankly, although I am sympathetic to the situation you're in, I think using a portable gasoline generator set for the use you propose is quite dangerous and a terrible idea. Sorry.