When I first got my T@B, I struggled trying to decide on the best solution to recharging the battery (which usually lasts about 2 days) when dry camping. Getting a small gas-powered generator was the most obvious choice, but I really didn't want to deal with hauling a filled gas can around or the mess of changing oil, etc (not to mention the mood-killer of listening and smelling a gas engine running when trying to enjoy the great outdoors).
So the more eco-friendly choice was to get a solar panel. It's certainly on my list one day, however, dry camping in the Northwoods doesn't always guarantee sufficient sunshine--- what would I do if I needed to recharge my battery on a cloudy day?
Well leave it to one of my fellow ingenious T@B buddies, Jay, to come up with a brilliantly simple alternative solution (and another T@B buddy, Jeremy, to perfect the idea even further). Jay and his wife often like to go sightseeing once they've set up camp, so Jay's idea was to bring a 2nd battery along and hook it up to his truck's 7-pin connector so that while they were out driving around, the spare battery would be getting charged up.
But that was only half of the brilliant solution! When they returned to camp, rather than have to fool with unhooking the T@B's battery and swapping it with the spare, Jay realized he could simply connect the spare battery to the T@B using the T@B's 7-pin connector cable.
Jeremy took this idea one step further and installed a "car-end" 7-pin connector directly into the spare's battery box so that you wouldn't even need to swap out a "car end" connector when attaching to the T@B for a "trailer end" connector when recharging the battery from the tow vehicle.
I wasn't quite as handy as Jeremy, so I just created a car-end connector cable to always keep attached to the spare battery. The battery, by the way, is an AGM self-contained model so that it's safe to carry around in the back of my enclosed station wagon.
Here are the components:
1. Make a cable with 2 "trailer end" 7-pin connectors. Inside the black cable cover are (2) 12 gauge wires to connect the 12v power and ground connections of the 7-pin.
2. Make a cable with 1 "car end" 7-pin connector (also used two 12 gauge wires to connect the 12v power and ground connections).
3. Connect the "car end" cable to the spare battery. In this setup, you can now connect it to the T@B's 7-pin connector cable to provide 12 volt power to the T@B.
4. Use the "trailer to trailer" cable to recharge the battery (My tow vehicle's 7-pin connector is on a cable itself that I can keep completely inside the car when not towing).