Is a Diode Required on the 12 Volt Pin for Charging a Trailer Battery

Published 09/11/2018

Question:

I use my auto hauler for more than just cars. Therefore, I am installing a solar charging system with a deep cycle battery to use 12v for lights and and other small accessories when the trailer is disconnected from the tow vehicle. The black wire from the 7-way plug supplies power when connected to the tow vehicle. Im thinking I would need a diode in the black wire lead between the tow vehicle and the solar battery. Will the Roadmaster Single Park Light Diode work in this case? Any guidance would be great. Thanks

asked by: Jon

Helpful Expert Reply:

You do not need to have a diode between the two 12 volt batteries on your trailer and tow vehicle but it is not a bad idea either. The Roadmaster Single Park Light Diode part # RM-690 will work perfectly for this. The factory 12 volt pin on most 7-way trailer connector is keyed so if yours is not or you do not have a factory 7-way then I do recommend using the diode.

expert reply by: Conner L