Quote Originally Posted by IamJEEP View Post
I researched a bit online and according to a couple of RV forums, 12g wire at 10amps of charge is all you need for a trailer battery. So I would say you can use the trailer 7 wire to charge you trailer battery with no issues.

Sal, I agree that a deep cycle would be the ideal battery here. Trickle charge is the way to go, but I think you would need a battery monitor to stop charging when full.
I think a proper battery charger would be the way to go to protect the trailer battery. That should work both ways protecting the starting battery as well and you can skip the isolator then as well.