Join Date: Aug 2006
Location: Arlington, VA
Thanked 14 Times in 12 Posts
Rep Power: 12
Camaraderie is right: do yourself a big favor and just buy an inverter large enough to handle the coffee maker, and hook it up directly to your house batteries.
It's clear from your remarks that you haven't yet done the research, and learned that a proper "4-way switch" able to handle shore power and generator power (30amps) as well as inverter power will cost a bundle. Furthermore, unless you have a knowledgeable friend qualified in marine electrical systems it's gonna wind up costing you some bucks....far more than the cost of the new charger you say you don't want to buy.
Small inverters are cheap, simple to install, and will do the trick for you.
The more complex route of tying in a (permanent, substantial) inverter to your boat's AC and DC systems will not only be costly in itself, but will raise problems such as potential for killing your batteries if, e.g., the hot water heater is left on while the inverter is switched on.