How to Power Enclosed Trailer Lights with Auxiliary Battery

Updated 04/13/2021 | Published 04/09/2021

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10 Gauge Wire - Blue Primary - Per Foot

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12 Gauge Wire - Black Primary - Per Foot

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Trailer Wiring Junction Box

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Question:

I would like to supply 12 volt power to the dome lights inside an enclosed trailer without draining my vehicle battery. Im open for other suggestions, but i guess i would like to have a separate battery for power. Do you sell an adapter that will hook up to a battery and supply a 7 prong trailer plug? Thanks for your time.

asked by: Brian

Expert Reply:

In order to provide lights with power outside of the tow vehicle battery you will need to add an auxiliary battery on the trailer like the Brightway # BRW34FR, as you've noted. There isn't an adapter, per se, so you will need to wire everything into the trailer; I can give you a general ideal of how it's going to need to be done.

I recommend cutting off the 7 way trailer plug and then wiring that into a junction box # 38656. From there, you'll connect the cut wiring for the trailer lights and brakes and wire in the battery behind the junction box on the auxiliary power circuit. From there, you'll connect the wiring of the lights to the battery and you'll have the correct setup.

If you need ring terminals you can use the Ring Terminal - 12-10 Gauge Wire - 3/16" Ring ID # 44-5310A; 10 gauge # 10-1-1 and 12 gauge # 12-1-1 wiring is also available by the foot, and heat shrink butt connectors # DW05745-10 can be used to make any wiring connections that are spliced together.

I've linked an article that outlines how a 7 way trailer plug is wired that you can use as a reference on this installation.