Hi. This is my first post here. I want to run an AC inverter off my car battery so I can get a higher wattage, but I don't want to worry about running down the starter battery. This crude and not at all to scale illustration shows you what I'd like to do:


I would have a switch of some kind to decide which battery gets power from the alternator (unless it can charge both at one time, I might get an aftermarket alternator with higher throughput if that is a better idea), then the battery in the trunk would charge off that alternator and would in turn supply power to the AC accessory.

Would this work? Would I need other parts? The second battery would not need to supply power to the rest of the car (although if it can without costing much more then I'm not opposed to that, but I figure just using it to power the inverter will cost less than incorporating it in with the rest of the car's power system). Should I use a switch to charge one battery at a time, or let both draw at once from the alternator? Should I get a better alternator? Would it be more efficient to keep the inverter close to the battery and run an AC cable to the back seats or to keep the inverter close to the back seat and run DC cables to it from the battery?

Thank you for your help.