Wiring for Power Tongue Jack

[SpeakEasy]

I'll be installing a power tongue jack. I do a fair amount of dry camping, which means I am frugal about my use of battery power. I selected a power tongue jack that uses less energy due to a ball-bearing design.

I am thinking of wiring it to use tow vehicle battery power rather than directly wiring it to my trailer's battery. I would use the ground and lights connections on a flat-four connector, and I would plug this flat-four connector to the tow vehicle's flat-four port when I want to raise and lower the trailer. (I realize the tow vehicle's lights would have to be turned on to power this circuit.) I figure any time I need to raise or lower the trailer, the truck will be right there, because we'll be arriving at a site or leaving a site.

What are the pro's and con's of this idea?

Thanks in advance.

-Speak

[SpeakEasy]

Accomplished the installation today - in between rain storms - and all is good. Wired it to the trailer battery, and will operate it while connected to the TV most of the time.

I am REALLY, really happy to have this new upgrade. I didn't realize when I bought the trailer a year ago that I would have to crank it up and down multiple times per camping trip to engage/disengage the weight distribution bars. My old and worn-out shoulder joint needs this power jack.

-Speak

[Vintage465]

Bobbo wrote:

downtheroad wrote:
Why not just just leave your trailer connected (or connect it) to your truck via the 7 pin connector and have the truck running whenever you are operating the jack?

My thoughts exactly. Wire the jack to the trailer battery, but leave the trailer hooked up to the TV with the engine running, and the TV alternator is supplying power.

I was thinking this all along. Long as the rig is plugged in to the TV and the charging circuit is bueno you're covered

[SpeakEasy]

Wow; awesome help given here. I truly appreciate all who've taken the time to give me their point of view.

On reconsidering the whole thing, I think I WAS overthinking it. I guess the thing that makes the most sense is to wire it in the "normal" way (to the trailer battery) and just leave the trailer connected to the TV electric whenever I'm raising and lowering.

Thanks all!

-Speak

[DrewE]

I think you're overthinking the power usage of the jack. It would use a fair bit of current, but how long do you run the jack for in a weekend? 30A (which I'm guessing may be larger than the actual current, though I don't know) for two minutes (a good bit longer than it takes to get the jack adjusted, I would think) works out to a grand total of one amp-hour of charge consumed.

It's the same basic reason why the water pump's power use is pretty low on the list of concerns: the run time is comparatively small, so the total energy usage is quite modest even though a nontrivial amount of power is required.

[GordonThree]

ScottG wrote:
If I can, I simply leave the TV attached and running while I raise the tongue.
Also, I really dont think there's sufficient current capacity on the light circuit to run the jack. Overloading a lighting circuit on a modern vehicle can be problematic.

x2 on this, my 2017 Ram HD struggles to deliver 10 amps on the trailer connector, I can't see it running my Barker tongue jack. That sucker is fused for 30 amps, and can draw pretty high if the tongue is stuck on the ball for some reason.

[Bobbo]

1995brave wrote:

SpeakEasy wrote:
Ah; good point. I didn't know that about the light gauge for taillights.

So, I would be better off using the hot (battery-charging) circuit on the 7-round Bargman? Seems like overkill in terms of a plug, but if it would work, I could live with it.

-Speak

Yes, the charge wire on the seven pin will work. It should allow you to pull around 30 amps or more.

After all, it is (or supposed to be) 10g.

[1995brave]

SpeakEasy wrote:
Ah; good point. I didn't know that about the light gauge for taillights.

So, I would be better off using the hot (battery-charging) circuit on the 7-round Bargman? Seems like overkill in terms of a plug, but if it would work, I could live with it.

-Speak

Yes, the charge wire on the seven pin will work. It should allow you to pull around 30 amps or more.

[ScottG]

If I can, I simply leave the TV attached and running while I raise the tongue.
Also, I really dont think there's sufficient current capacity on the light circuit to run the jack. Overloading a lighting circuit on a modern vehicle can be problematic.

[Bobbo]

downtheroad wrote:
Why not just just leave your trailer connected (or connect it) to your truck via the 7 pin connector and have the truck running whenever you are operating the jack?

My thoughts exactly. Wire the jack to the trailer battery, but leave the trailer hooked up to the TV with the engine running, and the TV alternator is supplying power.

[downtheroad]

Why not just just leave your trailer connected (or connect it) to your truck via the 7 pin connector and have the truck running whenever you are operating the jack?

[Jack_Diane_Free]

My original power jack quit working so I went to an industrial supply house (not RV parts store) and purchased a 3500 lb utility trailer power jack. It came with a 7 pin fit power cord and I just leave the truck running and plug it into the 7 pin receptacle on the truck. Works fine and does not consume trailer battery power. Yes there is an additional cord that just tucks under the propane cover when travelling and is no problem.

[SpeakEasy]

Ah; good point. I didn't know that about the light gauge for taillights.

So, I would be better off using the hot (battery-charging) circuit on the 7-round Bargman? Seems like overkill in terms of a plug, but if it would work, I could live with it.

-Speak

[1995brave]

I don't think it will work. Most vehicles taillights are wired with 18 gauge wire and fused for around 5 amps. You will probably end up blowing the fuse or burning up the taillight wiring in the vehicle.

[DutchmenSport]

SpeakEasy wrote:
Good idea, and simple enough to do. I'll do it.

But any tow vehicle with a flat-four port will work. I won't be modifying the tow vehicle's wiring in any way.

-Speak

You might want to add to your arsenal of "stuff" the 7 pin to 4 pin adapter plug for this very purpose. Not every vehicle is quipped with the 4 pin plug. Mine is not. I always keep a 7 to 4 adapter, especially since I also tow a 10 foot utility trailer that is wired for lights only.