Ya, the 1500 watt coffee pot is a killer. Even with 2-6 volt golf cart batteries your going to drain them quick. 1500 watts is as much as a space heater!! As far as using jumper cables to put a little bit of extra kick in your batteries a couple of times a year I see no reason you can't do it. On my last TT with a single battery I would hook up a jumper pack to give the battery a little bit of extra juice. That would gain me a extra day or more. Of course, I wasn't making coffee or nothing. Just running the lights.
I have no proof but, I do believe that modern alternators on vehicles don't need to be run as fast as they did on the old days to put out the same amount of power. I'm not saying they put out 100 percent a idle but, the put out a lot more at that speed then they used too. But, again I can't prove that.
