Installing a Trailer Battery Charge Line from Vehicle Trailer Connector

Published 10/03/2018

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Question:

charging battery on popup Hi - this answer was given by Reno H concerning charging the battery on a pop up: To maintain power to the battery, you would need to run a wire from the positive terminal on the trailer battery to the power wire on the 7-way. I would recommend using 10 gauge wire, part # 10-1-1, and connecting to the Black wire on the trailer 7-way, or the pin in the 11 oclock position when looking at the front of the connector to the positive battery terminal see FAQ. You would then connect the negative terminal to a clean metal surface on the trailer frame for a ground connection so does that charge the battery when hooked to the vehicle ?

asked by: Don L

Expert Reply:

To charge your trailer battery when you look at the 7-way trailer-side connector the 11 o'clock pin will mate up to your 12V signal from your vehicle. With most trailer connectors like # H20043 this will be the black wire. That black wire simply connects using 10 gauge butt connector like # DW05745-5 to 10 gauge wire sold by the foot # 10-1-1 which will connect to your trailer battery positive terminal. As you stated the negative terminal of the trailer battery will be connected to the metal frame with a bare metal to metal connection for a ground. If you do not have the 12V power on your vehicle side, you can use the # 30717 and connect the white wire to ground and then the black wire to # 10-1-1 run up to your engine compartment. Before connecting to the positive battery terminal, you will need to add a circuit breaker # 9510.

This will allow your trailer battery to receive a maintenance charge while connected to your vehicle. This is a very slight charge depending on your vehicle alternator of between 2 and 4 amps at 12V. This will not charge a dead battery, but will slowly charge and maintain your trailer battery.

If you want to really charge a depleted battery, you will need a different setup like the DC to DC charger # 331-BCDC1225D which will give you up to 25 amps at 12V to charge a depleted battery.