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Wlasota 12-31-2014 03:04 PM

Temporarily Powering a 5th Wheel from a tow vehicle.
In the winter I remove both batteries from my 36CKTS.
I thought for the few winter inspections I make at the storage facility I would just plug the tow power cable from the 5th wheel into my tow vehicle to provide power for lighting only. When I attempted this the interior lights didn't come on. The battery disconnect switch was in the ON position. I have not had time (and it's too cold) to trouble shoot.
Shouldn't what I tried work?
The tow vehicle charges the batteries successfully when towing.

fonzie 12-31-2014 03:08 PM

Did you leave your tow vehicle running when trying the lights? Maybe it needs to run....also are all your 12 volts cables connected together at the battery box eg: all positives together and all negatives together?

Dave_Monica 12-31-2014 03:47 PM

Another thing to check is if you have the relay or fuse installed in the truck to provide 12V power at the 7 way plug. Easiest way is to check at the truck's plug for 12V power between pin 4 and pin 1 (ground) with the truck running.


Wlasota 12-31-2014 04:21 PM

Thanks for the suggestions. The battery cables for both batteries are isolated (insulated) during storage.

donniedu 12-31-2014 05:49 PM

Cant do it! Charge line only supplies minimal current to recharge the house battery while under way. Leaving it connected without a battery in place does not complete the circuit for lights. Take a battery with you and if nothing else using jumper cables connect it. Take it home with you when your done

J_KHawthorne 12-31-2014 07:10 PM

Guess it must depend on the unit. I store my battery on a trickle charger in the garage over the "winter" here while at our winter home in southern Arizona. The trailer is at a storage unit without power. Lights and slides operate when plugged into the 7 pin off the truck. Slides are a little slower maybe, but they work!

Crusadernoob 12-31-2014 07:13 PM

Ours will power up also, truck must be running but that is how we winterized, off the truck 7 pin.

38FLCamper 12-31-2014 09:02 PM

Should it work - yes.

Sounds like a wire is not connected, possibly a ground wire from the pigtail into the rig.

It should provide basic lights, might operate the slides on a good day, and some leveling systems. The size wire for the "charge" line in a tow vehicle is too small to provide much (even for charging really) power to the camper. Again it should work just be careful with the power use.

Using a volt meter check the power at the battery terminals - should be 12 Volts. If not check power at the plug.

WeRCreekers 01-01-2015 11:31 AM


Using a volt meter check the power at the battery terminals - should be 12 Volts. If not check power at the plug.
OK, I think the OP said his batteries are removed from the coach and are in his garage back home. In my CC, the battery has to be installed (or at least in the circuit) for this to work. The 12V lights are operated from the battery. Plugging in my truck without the battery installed will not power the lights. It will however, slowly charge the battery if it is installed. So, at least for me, donniedu is right. Some of the responders in this thread are not CC owners and the OP is.:cool:

Campingnut 01-01-2015 11:47 AM

I also need a battery installed for anything to work in my unit.

kinzoo 01-01-2015 11:52 AM

You need the batteries installed...

Eaglelover 01-01-2015 01:22 PM

Temperory Power
How about taking jumper cables and connecting to the truck battery and to the battery cables on the rig?? Frank

kinzoo 01-01-2015 01:38 PM


Originally Posted by Eaglelover (Post 757812)
How about taking jumper cables and connecting to the truck battery and to the battery cables on the rig?? Frank

That may work also,
Thanks Frank

WeRCreekers 01-01-2015 01:41 PM

I'd think that would work but the OP stated he has isolated and insulated his battery cables (IOW wrapped them in tape?). So probably too much trouble. But a good flashlight would work. :)

arice24814 01-01-2015 05:03 PM

Mine is in storage right now, i use the truck to power the slides, and the onboard for the interior light(also recharges the units batts .leave it running) works great. If i just try to use coach batteries to open it up for inspections and just general cks it drains them quick. But i have to have the batteries installed to and switched on for the lights. only runs the Slides

rvguy66 01-01-2015 08:10 PM

using the slides w/o batteries
A master tech told me the main cause of slide failure is caused by operation with low power. IOW, low or no batteries. The converter doesn't provide enough power. They may move, but they are being damaged. Like running the A/C on only 20 amps.

Campingnut 01-01-2015 10:08 PM

Any time you use any electric motor with lower than recommended voltage you run the risk of damaging it.

dieselguy 01-29-2015 12:27 PM

For those of you who when in storage operate slides solely off your pigtail connected to the truck ... you're putting an insane current draw upon a 14 gage (maybe 12 gage) charging wire on your tow vehicle. That's why it is s-l-o-w moving and lights dim down. It doesn't do your pump motor any good. I'd bet you could barely touch the TV charging wire with a bare hand after opening the slides.

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