when I get a long term, in the shadows type campsite, and my solar panels are doing little to no good, I've plugged into the power source on my tailgate and I idle my truck for an hour or so. It certainly doesn't get the award for cost bennifit as far as gas goes but it works guite well. Oddly, it's also quieter than a lot of generators I've heard. I've seen others use jumper cables directly to the battery. I don't have an AC unit on my 17 foot so I'm just powering water pumps, refrigerator, fans, LED lights and electronics.