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Author Topic: Isolator needed between truck & camper?  (Read 3978 times)


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Isolator needed between truck & camper?
« on: May 20, 2013, 11:29:08 PM »
I noticed, when I have the camper plugged in to the truck, one of the wires to the camper batteries, already has power to it.   I'm thinking there is no isolator within the wiring system to the camper, but have no electrical experience, so does anyone know how I could add an Isolator myself?   Just trying to save a few $$.
Also, does this sound like an 'Isolator' issue?     I'm wondering if it was wired this way, so the alternator would charge the camper batteries while driving...or will an isolator allow that anyway?

Thanks in advance.
2008 Tiffin Phaeton Motorhome
2014 Honda CRV (Towed)
'Air Force One' car braking system.

Lou Schneider

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Re: Isolator needed between truck & camper?
« Reply #1 on: May 21, 2013, 01:55:26 AM »
If the 12 volt line is live to the camper when the truck's ignition is off, then yes you will drain the truck battery along with the camper's house batteries when you aren't connected to electricity.

You can install an isolator, either a relay that only connects the 12 volt line when the ignition is on and the engine is presumably running to charge the camper battery, or a diode isolator that lets the alternator charge both batteries but otherwise keeps the two systems separate.

Or you could just unplug the camper's electrical cord from the truck when you set up camp and reconnect it when you're ready to leave.
« Last Edit: May 21, 2013, 01:59:57 AM by Lou Schneider »


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Re: Isolator needed between truck & camper?
« Reply #2 on: May 21, 2013, 09:38:49 AM »
The Ford (96) that I had had a built in relay  (on the Fuse panel) that turned the camper off when the ignition was off. That camper I simply plugged into the 7 pin RV plug at the rear of the truck. I believe Most Fords are that way if you use the RV plug at the back.

If your not hooked to the RV plug all bets are off on how it's wired.

I now have a Dodge and there is No Relay on them. So all 3 batteries are hooked together. It's been this way for the last 7 years. I have set for up to 4 days at a time and never yet had dead batteries. I do have LED bulbs but still run the Furnace, TV and Computer as needed.


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Re: Isolator needed between truck & camper?
« Reply #3 on: May 27, 2013, 04:45:09 PM »
Id be suprised if your Ford didnt come with an isolator-probably does if it has factory tow package, its a lil relay box attached to side of main fuse box in engine bay.
pic of earlier Ford relay (new to forum dont see pic insertion, linked as attachment.
When it showed hot was truck key on? The bumper plug bout 1:00 is charge line-should be no power with key off. Often as not the bed plug is just spliced into trailer plug. Unless someone wired it to direct hot, I suppose a relay could stick closed, not likely.

Adding an ign. controlled constant duty solenoid easy enough.  Would allow also running a larger charge line to camper.
« Last Edit: May 28, 2013, 10:28:39 AM by AnEv942 »
2001 Ford F250
2001 Elkhorn 9U camper


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Re: Isolator needed between truck & camper?
« Reply #4 on: June 08, 2013, 11:46:50 AM »
My 06 Lance was equipped with a solenoid type isolator in the camper electric area, and I ran 8 gauge wire  forward to the battery, fused on both ends.
The solenoid style isolator, which was a stock part on the Lance, never worked satisfactorily for me, despite 2 factory certified replacements. It had resistance, became quite hot to the touch, and did not do the job.

My battery was never low after I replaced it with a heavy duty rotary switch designed to turn battery systems on and off (NAPA) and in 6 years   never had another problem of finding my camper battery low after a days travel. A "telltale" ribbon, which showed on the camper step reminded me to turn off the switch when camped.

No automatic isolators for me, the KISS System (keep it simple stupid) worked perfectly.