Took my Flagstaff 228 on a maiden voyage this weekend with no hookups. Ran the furnace at 65 degrees for two nights plus some water pumping (no use of lights) then towed home (2.5 hour drive). I was amazed to find my battery charged back up to 100% (12.70 volts) after the tow home running on accessory wire from 7-pole. I also ran the vehicle connected to the PUP for 30 minutes in-between night one and two.
I say amazed because I've read about 25 forum posts on the 'net insisting that the accessory wire will provide a trickle at best and should not be relied on to actually charge the trailer battery due to physics of the TV alternator and battery design.
So, did I experience a miracle or can a TV actually charge a trailer battery pretty well? My dealer thought so and actually recommended simply running the car for 30 minutes each day to recharge.
I do realize that running my vehicle at idle is a terrible waste of energy, and I normally wouldn't have done this except that I accidentally left the multimeter at home and couldn't check on remaining power after the first night. I haven't bought a generator yet either. But I didn't want my family to experience a bad second night, or it might have been their last