Best Way to Provide Power to Electric Trailer Tongue Jack

Question:

I have a 2000 Coleman pop up trailer with an aftermarket electric jack. It is currently wired to one of the 12 volt legs of the inverter and only works with shore power. Id like to wire the jack to the 12 volt power coming from the tow vehicle as well. In other words, at present you cannot use the jack without a connection to shore power. Unfortunately, I cannot find wherever the existing wire from the 7 pin connector terminates in the frame, nor can I find the connection to the inverter 12 volt leg that the jack is wired to. I would have to tear the interior apart to find either these. I am not willing to do so at this point One possible solution is a single pole double throw switch in a junction box on the tongue. I was thinking about totally severing the 7 pin connector and wiring it through the junction box with the switch. Would this be a viable option? Also, should I use a heavy duty switch, or should I put in relays?

asked by: Roland

Expert Reply:

In a typical RV-style 7-way the 12V charge circuit is carried on the pin at the 1-o-clock position as you look at the socket from the rear of the vehicle. Please refer to the linked photo. The 12V feed from a vehicle 7-way can deliver just enough trickle-charge current to maintain a strong battery while you're on the road, but it is not the best way to power a trailer jack.

The best way to power a trailer-mounted 12V tongue jack, like the Stromberg Carlson # SC63VR, is to install a dedicated battery on the trailer. The dedicated battery will give your jack the current it needs to operate at its rated capacity/speed without putting the vehicle battery at risk of depletion. The 12V power feed from the vehicle will maintain this battery while you drive.

You certainly can wire a battery along with your shore-power inverter so that either can power the jack but we do not recommend directly using the vehicle's 12V auxiliary trailer circuit for this purpose.

expert reply by: Adam R