Question Was Asked By - Dave O

Can a Trailer Battery be Charged While the Trailer is Being Towed

Question:

I am wiring a small mini travel trailer. It has no brakes, or back up lights, but it does have a 12V battery. I have a 4 pole connector and purchased the 7 pole connector. I want to be able to charge the trailer battery while towing but Im not sure which color wire to use or how and where to wire this wire. I do know that I will have an in-line fuse but again, not sure of the size of fuse to use. How do I accomplish this wiring project???

asked by: Dave O

Expert Reply:

First, the vehicle must be upgraded to the 7-pole, # 30717, if it does not have one already. This will allow for the 7-pole on the trailer to connect. The vehicle will also need a 40 amp circuit breaker (part # 9510) and 10 gauge primary wire (part # 10-1-1). Ten gauge wire handles 50 volts or less, but is well within the range for your needs. The color we carry in 10 gauge is blue, color does not matter as long as you are aware of what color is being used, and where you are attaching it. It is inexpensive, so make sure you measure the length of the vehicle and account for the bending going from the vehicle battery back to the 7-pole in the trailer so you order plenty. You may want to order some wire frame clips (# 464600) to attach the 10 gauge wire to the frame all the way to the rear of the vehicle.

To hardwire the vehicle to be able to charge the 12V on your trailer, you will attach the 10 gauge wire to the positive terminal on the battery, run the wire back to the 7-pole on the vehicle, and insert it into slot number 4, (black), or slot number 7, (auxiliary, orange). Please mount the circuit breaker under the hood of the vehicle, in someplace convenient. This will keep the battery from overloading.

Regarding the trailer, it is my understanding you have wired your 4-pole to a 7-pole (part # PK12706). The 10 gauge wire goes into slot number 4, (black,red), or the center for auxiliary, (orange). Again, you will be running the blue 10 gauge wire from the 7-pole to the 12V battery. This will connect on the positive terminal on the battery.

expert reply by: Renee B

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