How to Wire the 7-Way Charge Wire to Trailer Winch Battery and Protect the Vehicle Battery

Updated 02/28/2012 | Published 02/25/2012

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Starter Solenoid - SPST - 12 Volt - 100 Amp - Continuous Duty - Grounded

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Pollak Circuit Breaker - Cycling/Automatic Reset - 40 Amp - Straight Mount Bracket

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Question:

I have a car trailer with a winch on it, much the same as option 2. I want the battery to charge from the tow vehicle. Its too eazy to forget to unplug to cord when you are doing this. Can I install say a diod so the winch cannot damage the vehicle wiring?

asked by: Garry

Expert Reply:

For the best protection of your vehicles battery and wiring we recommend installing a 40 amp circuit breaker, # PK54540, inline on the charging wire going from your vehicle battery back to the trailer connector on your vehicle. If your vehicle has a factory 7-Way connector the charge line will be protected by a fuse in the power distribution box under the hood so adding a circuit breaker would not be needed.

If you are concerned about drawing power from the vehicle battery when the vehicle is not running, if the trailer is left plugged in, you can install and battery isolation solenoid, # PK5231201, inline on the power wire going back to your 7-Way connector. I added a photo showing how the wiring would be installed.

On the 2001 Chevrolet Silverado, the power wire for your 7-Way will be connected to the power stud at the front of the power distribution box under the hood, see photo. You will install the isolator inline on this wire and splice a wire from the smaller post on the isolator into a switched ignition source so that the trailer cannot draw power from the vehicle battery when the vehicle ignition is off. When the ignition is on the isolator will close allowing the vehicle charging system to help maintain the trailer mounted battery.

expert reply by: Robert G