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How To Maintain Trailer-Mounted Winch Battery Using 7-Way 12-Volt Accessory Pin


how to charge battery for winch on my boat trailor, can i run a wire from truck battery to hitch aux black wire with inline fuse at trailor hitch 7 point plug or can i use the purple backup wire on truck plug wire to black aux wire on 7 point plug to charge battery for winch


Expert Reply:

I do not recommend using the accessory circuit if it is attached to the reverse lights as it will only provide power when the vehicle is in reverse. But you can connect the 12 volt accessory pin to the vehicle battery using the following method. First, on the towing vehicle, you will need to install a battery isolator, # TR118665. The flow of current will go from the vehicle battery to the isolator. From the isolator it will go along a length of 12 gauge wire, # 12-1-1, to the vehicle side trailer connector via a 30 amp circuit breaker.

Next, 12 gauge wire will need to run from the trailer side 7-Way to the positive Trailer battery terminal. If the winch came with a circuit breaker it will need to go between the winch and positive battery terminal on the trailer battery. The trailer battery will need to be grounded to the trailer frame as well.

I have included an FAQ article on winch wiring that should be helpful. Please note that this method will maintain the battery, but will not provide an effective charge. A the trailer battery should be periodically charged using the appropriate size charger. I recommend the CTEK MULTI US 7002 12-Volt Universal Battery Charger, # CTEK56353.

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