How To Charge Trailer Battery From a Chevrolet Silverado With a 7-Way Connector

Updated 10/21/2011 | Published 10/20/2011

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Pollak Black Plastic, 7-Pole, RV Blade-Style Trailer Socket - Vehicle End

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10 Gauge Wire - Blue Primary - Per Foot

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Hook Probe Circuit Tester

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Question:

I have put a electric tongue jack on the a frame of my cargo trailer. Inside the trailer I have put a deep cycle 12 volt battery to run the tongue jack. How can I use the trailer connector 7 pin on my 2500hd Silverado to charge the battery in the trailer as the truck is pulling the trailer.

asked by: Bill L

Expert Reply:

To keep the trailer battery charged you will need to run a 10-gauge power wire like the part # 10-1-1, from the 12-volt power pin (# 4 terminal at 11:00 position) on your trailers 7-way connector, to the positive terminal on the trailer battery. Now when the trailer is connected and you are towing, the tow vehicle will provide a maintenance charge to the trailer battery. It will not charge the battery from a discharged state.

You will want to test the # 4 terminal at the 1:00 position on your vehicles 7-way connector for power with a circuit tester, part # PTW2993. This is the terminal that will supply the 12-volt power to your trailers 7-way connector. If it does not show power, you may need to insert a fuse and/or check that the wire is connected to a power source by tracing the wire back.

You will also want to unplug the 7-Way trailer connector from the Silverado when it is not running. This will keep the battery in the Silverado from being discharged.

To be able to fully charge the trailer battery from a discharged state you would have to use the NOCO Genius Mini # 329-GENIUS5. This charger can be used to fully charge the battery and then you can maintain that charge with the vehicles charging system.

I am including a link to a FAQ page on trailer wiring and a link to a video review of the NOCO charger.

expert reply by: Jeff D