Troubleshooting 12 Volt Accessory Circuit Not Charging Trailer Battery

Question:

I have a 2017 expedition king ranch with the HD towing package. I also have a 23 foot airstream trailer with a battery bank for house loads. I do not believe the truck is charging the trailer battery. How do I correct this? I have had the trailer battery down to 11.5vdc, hooked up the trailer and drove home 150 miles - found battery not charged. I do find several fuses labeled towing controller, but I think they are all for the brakes. Any help? I there an adaspter I need to buy?

asked by: Larry M

Helpful Expert Reply:

Have you used a circuit tester like the part # PTW2993 to make sure there is voltage on the 12 volt accessory pin of your 7-way? This would be the circuit that would charge the trailer battery and is in the 1:00 position of your truck's 7-way. Typically a fuse under the hood for the 12 volt accessory circuit is normally what causes this to not be active.

This circuit is normally not powerful enough to charge a bank of batteries so a BCDC charger like the part # RED96FR would be a good choice to give the circuit the ability to provide a better charge on the bank.

expert reply by: Jameson C