Towing A 2014 Ford Edge FWD

I tow a 2014 Ford Edge FWD. I use Brake Buddy brake controller. I do have the car wired to get a charge from the motor home to charge the car battery. There are times when after towing the car for 4 or 5 hours, I find the car battery dead. I use a 6-way plug on the car. There could be an issue with the split pins in the 6-way plug for the battery charge. Also, with the key in the car's ignition, the dash is still lit up. This could contribute to the drawing down of the battery. Do I need to pull the fuse for the dash, Could it be #11 fuse? What can I do to make sure I have a good connection from the motor home to the car and get rid of the split pin issue, the split pin closing up and not making a good connection.