Can a Trailer Battery be Directly Connected to the 12 Volt Circuit on a 7-Way Connector

Updated 03/02/2012 | Published 02/28/2012

Question:

I have a 2012 Tundra. I have a wire in my 7 pin connector that supplies 12V power only when the ignition is on. I is a 10ga wire on a 40 amp circuit.Can i wire this directly to my trailer battery without causing any damage.By doing this is will make 1 terminal on my trailer 7 pin hot all the time even when disconnected from truck unless i pull the inline fuse on trailer battery. Is this anything to be concerned about.Thanks for any help you can give.

asked by: Bill E

Expert Reply:

First, you can connect the 12 volt circuit directly to the trailer battery. However, the wiring in the trailer wiring package is not able to charge up the battery, it can only maintain its current charge level. To up charge the battery, you would need to use a battery charger like # CTEK56353.

Having a hot 12 volt circuit when the trailer is disconnected is not going to be a problem but if you want to be absolutely sure there is no power loss or back feeding issues, I would recommend disconnecting the trailer and/or pulling a fuse or installing a switch inline on the power wire going to the trailer battery if you are going to be stopped for long periods of time.

expert reply by: Michael H