I'm going to be doing a lot of dry camping this year with my pop-up camper. I will be using the truck to charge the batteries, and run the fridge while en route. When I am stopped, I am thinking I won't get more than 2 days out of my battery, less if my wife is using her hairdryer. I have 2 methods available to recharge the batteries...
1. Plug the 120V / 120V converter into the 120V inverter power in the box of the truck, idle the truck. (converter draws 360w max)
2. Plug the 7 pin wire harness, and idle the truck.
I think that method 1 will charge the battery quicker, and to a much higher level. Mostly because all voltages are regulated up this way. Method 2 is more conventional, but at idle, I doubt the alternator will produce enough voltage to charge the battery fully. I think the combination of voltage drop, and the alternator not cranking out full voltage, will be slow, and not terribly effective.