Hopkins 5-Way Vehicle and Trailer Connectors # HM47890 Recommendation For Charging Trailer Battery

Published 05/06/2011

Products Featured in This Question

Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(94)

$48.20

Adapter 4-Pole to 7-Pole and 4-Pole

(660)

$62.08

7-Way Round RV Style Trailer Connector - Trailer Side

(377)

$13.57

Question:

We had the Hoppy electronic power taillight converter installed on the vehicle last year. We purchased a 1988 Jayco popup. The vehicle and popup both have the 4-pole flat connector. I figured out all the lights on the trailer except the black wire on the trailer to the trailer battery. How do I get power from the vehicle to charge the trailer battery while driving?

asked by: Marvin G

Expert Reply:

You will need to run a wire from the positive post of the battery on your 2005 Jeep Liberty to the black wire that runs to your trailer battery. This will charge the battery of your trailer while the wire is connected.

I would recommend you cut off the the 4-ways that are on your vehicle and 1988 Jayco popup and then install 7-ways instead so you could have a designated trailer battery charging circuit that would charge your trailer battery when it was connected.

For this, I would recommend you get a Adapter 4 Pole to 7 Pole and 4 Pole, part # 37185.

I would recommend you run 10 Gauge Wire, part # 10-2-1, from the positive battery post on your Jeep to the 1 0'clock position of the # 37185 as your looking at it and then plug the 4-way from your Liberty into the four way connector of the # 37185.

Now you will want to wire a 7-Way Round RV Style Trailer Connector, part # A7WCB, to the four wires that were run to the old 4-way and then run the black wire that runs to your trailer battery to the post that is in the 11 o'clock position of the connector as you look at the front of the connector.

I attached an FAQ on trailer wiring for you to check out also.