Can the 12 Volt Circuit on a 7-Way Connector be Used to Charge a Trailer Mounted Battery

Question:

I have a pequea c 1500 dump trailer and i would like to run 12 v to the battery from the truck. I have a 05 ford superduty with power already at the 7 way plug. Can i just run a wire from the plug to the positive side if the battery or will the battery back feed to the truck

asked by: Tyler R

Expert Reply:

The 12 volt circuit on a 7-Way trailer connector is only enough to provide a maintenance charge to a trailer battery. It cannot charge it up. But yes, you can attach the 12 volt circuit wire from the trailer connector to the positive battery terminal on the trailer. There should not be any back feeding issue.

You will not be able to charge up a trailer mounted battery from the tow vehicle because the distance from the front of the vehicle to the trailer battery is too far and most all vehicle alternators are not strong enough to push back the amperage required to charge up a trailer mounted battery.

The exception is if it is a small breakaway system battery because they are rated much lower than the larger 12 volt batteries. To charge up a battery the best solution is an AC powered battery charger that you would use to charge up the battery prior to using the trailer. I recommend CTEK charger # CTEK56353. Several of us here use this charger and it works beautifully and will not overcharge a battery. I have linked a help article on battery chargers for you.

expert reply by: Michael H