How to Power Trailer Lights from Battery when Not Connected to Tow Vehicle

Updated 05/19/2015 | Published 05/18/2015

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Pollak Medium-Duty Toggle Switch - SPST- On-Off - 12 Volt - 20 Amp - 11/16" Handle

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$7.24

Roadmaster Single Park Light Diode

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Question:

I want to be able to turn on my horse trailer lights when not hooked to vehicle ....what to I need to know besides 2 diode and is that the same as battery isolator?

asked by: Kevin R

Expert Reply:

A battery isolator will cut off power once the solenoid is energized from another source. Diodes on the other hand only allow power to flow one way.

What you will need to do is run a power wire or wires from the positive battery terminal on a trailer battery to a switch such as # PK34571. Then you would run another wire from the switch to a diode # RM-690. Then run a wire from the diode to the trailer wiring for the lights you want to power.

Depending on what lights you want to use you may need more than one diode. If you just want the running light to work then you would just need the one diode.

I have included a picture illustrating this for you.

expert reply by: Michael H