How to Charge A Trailer Battery When Connected to Tow Vehicle

Updated 12/02/2014 | Published 12/01/2014

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10 Gauge Wire - Blue Primary - Per Foot

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Bulldog Winch Rear Wiring Kit - Quick Connect to Terminal End - 3 Gauge - 16' Long

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7-Way Molded Trailer Wire Connector - 3' Long

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Question:

I have a basic no brakes trailer with standard 4 pin electrical hookup. I want to have a electrically self sustaining with deep cycle batterys trailer for internal power when disconnected and then charging when connected. The tow vehicle has a circular 7 pin connector. The question is: What items would I need to make a system as described above including batteries single 12v or dual 6v

asked by: David B

Helpful Expert Reply:

What you are going to need to do is install a 7-way on your trailer so that you can run a 12 volt accessory circuit from the connector to a battery like you are interested in doing. You should note that this will only maintain a fully charged battery. For this route you will need a trailer side 7-way # H20042 and a length of 10 gauge wire to run to the battery. For that you would need part # 10-1-1 sold by the foot.

If you are looking for something to actually charge the battery on your trailer while your trailer is connected you would need something like the part # BDW20043. This will run a thick gauge wire from your vehicle battery all the way to the trailer battery and will put a decent charge from your vehicle alternator when the wiring is connected.

expert reply by: Jameson C