Tow Vehicle running three way fridge now.

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

HessyBear

Member
Joined
Sep 27, 2021
Posts
7
Location
Oklahoma
So, I had my popup trailer serviced at a local trailer shop. They were supposed to be checking the bearings and packing them.

They let me know that they do a thirty point inspection on all trailers they service, which was fine with me, but I asked that they call me before they do anything to the trailer other than service the bearings.

The guy calls me a few days later to let me know the trailer is ready, and they fixed my brakes and wiring on top of servicing the bearings. This kind of irked me, as my brakes and lights worked fine when I dropped the trailer off and I specifically asked that they call before doing any additional work. He claimed that the wiring had to be redone and it was causing the brakes not to work, which was not the case when I dropped off. I was really only interested in them checking the brake shoes and magnets. I brought this up, but just paid the bill and decided not to bring the trailer back to this shop again.

When I went to hook up, I do a walk around inspection, and the lights are not working. I pull it up and let the guy know the issue. They pull it into the shop and work on it. They let me know that the light issue is resolved, and it was a ground on my tow vehicle. That doesn't sound right to me, as they everything worked fine when I dropped it off and they had just "fixed" my wiring. I didn't say anything though as he didn't try to charge me even more.

Now, I load up the camper to take it out this past weekend, and when I hook up the new seven pin they installed, I hear the fridge small fan kick on, and the pilot click to light propane. I do not have a battery on the trailer for a DC current, so the only thing that can be kicking this on is the tow vehicle. I know for a fact that seven pin did not kick on the dc current before having the trailer serviced.

My issue with this is that in my limited experience, I haven't heard of this being something that should be happening. What if I forget to turn my propane on before heading out? Is the fridge going to try and run from the dc side off my tow vehicle? Should I be worried about the trailer pulling power from my tow vehicle and alternator?

Any wisdom and/or advice is greatly appreciated.
 

Oldgator73

Well-known member
Joined
Dec 28, 2017
Posts
3,530
Can you turn your fridge off manually or pull the fuse? But as far as the truck energizing your fridge while towing your trailer should not pose a problem. Only problem would occur if you stopped for an extended time your truck battery might run down. You mention your trailer does not have a battery. How does your fridge work when your camping? Is it a two way or three way?
 

regval

Well-known member
Joined
Jun 4, 2015
Posts
425
Location
Lawrenceville, Georgia, USA
“and when I hook up the new seven pin they installed”

Not all trailer 7 pin connectors have the 12V pin wired to the trailer battery. If the shop assumed it should have been wired so they could test the brakes without a tow vehicle attached, they may have attached a wire to the 12v pin.
Some shops have a tester that plugs into the trailer 7pin “connector and uses the camper’s 12v battery to supply power to the tester so that it can apply brake power and turn on brake and running lights. If your camper didn’t have an installed battery, they could have installed one temporarily or used a jump box. If their tester failed to work, the shop would likely assume the connector “was bad” and fixed what was not really broke. That’s my 2 cents
 
Last edited:

HessyBear

Member
Joined
Sep 27, 2021
Posts
7
Location
Oklahoma
Can you turn your fridge off manually or pull the fuse? But as far as the truck energizing your fridge while towing your trailer should not pose a problem. Only problem would occur if you stopped for an extended time your truck battery might run down. You mention your trailer does not have a battery. How does your fridge work when your camping? Is it a two way or three way?
Thank you for the response.

It is a three way.

I cool it off a few hours before we head out with AC power. It seems to prefer propane and cools faster that way, but I usually run it off of shore power when we get to our destination.

Adding the DC current was a future project, but as the only thing we really needed it for was allowing the fridge to cool via propane while on the road, it was on the back burner. Local State parks with hookups are the only places we are camping in the near future.

I will check to see if the fridge still gets power when the tow vehicle is not running. That will definitely be something I need to monitor.
 

Lou Schneider

Site Team
Joined
Mar 14, 2005
Posts
11,167
I do not have a battery on the trailer for a DC current
That is odd. I know it's just a pop-up, but if it has electric brakes there should also be a breakaway lanyard and a battery to activate the brakes if the trailer becomes disconnected from the towing vehicle.

Do you have a brake controller in the tow vehicle? If you don't, the trailer may have surge brakes which are mechanically activated when the trailer pushes against the tow hitch. In this case the brakes have no connection to the trailer's electrical wiring.
 

HessyBear

Member
Joined
Sep 27, 2021
Posts
7
Location
Oklahoma
That is odd. I know it's just a pop-up, but if it has electric brakes there should also be a breakaway lanyard and a battery to activate the brakes if the trailer becomes disconnected from the towing vehicle.

Do you have a brake controller in the tow vehicle? If you don't, the trailer may have surge brakes which are mechanically activated when the trailer pushes against the tow hitch. In this case the brakes have no connection to the trailer's electrical wiring.
The trailer does have electric brakes and a breakaway lanyard. There is also a breakaway box installed on the trailer because there is no battery currently installed. Now that I think about it, maybe the refrigerator is pulling current through the breakaway box when the lights are hooked up to tow vehicle.

I do have a brake controller in the tow vehicle.
 

John From Detroit

Well-known member
Joined
Apr 12, 2005
Posts
25,244
Location
Davison Michigan
Ok: They installed a new 7 pin connector.....

When you plug in you hear the fridge start on PROPANE (You said it's a 3 way but it's running on GAS,, Most today are two way Gas or 120)

You also said you do not have a battery in the trailer (Which depending on where you live might be a violation of the vehicle code, explanation follows)

When you plugged in the TOW Vehicle delivered 12 volts to the trailer via the battery charge lead. The Fridge was ON. but no 12 volts. so now that it has power... It began operation.

NOTE: The tow vehicle can not power a 3-way on DC but it can on GAS.

Now the battery part: If the trailer is heavy enough to require brakes. then there must be an "Emergency breakaway" system. this is the small cable that runs between a box on the tongue and the tow vehicle. This system uses the TRAILER's battery to lock up the brakes should the trailer become unhitched while moving.

NO battery = No breakaway system = Equipment violation.
 

HessyBear

Member
Joined
Sep 27, 2021
Posts
7
Location
Oklahoma
Ok: They installed a new 7 pin connector.....

When you plug in you hear the fridge start on PROPANE (You said it's a 3 way but it's running on GAS,, Most today are two way Gas or 120)

You also said you do not have a battery in the trailer (Which depending on where you live might be a violation of the vehicle code, explanation follows)

When you plugged in the TOW Vehicle delivered 12 volts to the trailer via the battery charge lead. The Fridge was ON. but no 12 volts. so now that it has power... It began operation.

NOTE: The tow vehicle can not power a 3-way on DC but it can on GAS.

Now the battery part: If the trailer is heavy enough to require brakes. then there must be an "Emergency breakaway" system. this is the small cable that runs between a box on the tongue and the tow vehicle. This system uses the TRAILER's battery to lock up the brakes should the trailer become unhitched while moving.

NO battery = No breakaway system = Equipment violation.
There is a breakaway box installed with a battery dedicated to the electric breakaway system, independent to a DC circuit.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
74,620
Location
At our Silver Springs FL home
There is a breakaway box installed with a battery dedicated to the electric breakaway system, independent to a DC circuit.
That's unusual but OK if that's what you want. There's no reason I can think of to dedicate a battery solely to the brake system.

In any case, the fridge requires 12v power to operate in any mode, i.e. 120v, LP, or 12v. The fridge circuit board is 12vdc powered.
 

HessyBear

Member
Joined
Sep 27, 2021
Posts
7
Location
Oklahoma
That's unusual but OK if that's what you want. There's no reason I can think of to dedicate a battery solely to the brake system.

In any case, the fridge requires 12v power to operate in any mode, i.e. 120v, LP, or 12v. The fridge circuit board is 12vdc powered.
The breakaway system has to have a power source. Because I do not have a DC circuit power supply installed yet, the breakaway system has a battery dedicated to it. See the attached picture for that set up (the box holds the dedicated battery for the surge brakes and has a tester built in). I believe that this is more common on car haulers etc that do not need a power source other than for the surge brake system, and much less common on a camper because most people have a battery hooked up to the DC circuit.

I bought the camper used, and the surge brakes were not working due to no power source. The brakes themselves worked fine when hooked up, but without the power source, the surge brakes would not have worked.

The trailer shop is the one who installed the breakaway system without notifying me beforehand. I wish they would have called me before they did that, and I would have elected to install a deep cell battery on the DC circuit instead of the breakaway system with a dedicated battery, but that is a conversation for another day I suppose.

It was just odd to me that the seven pin connected to my tow vehicle is powering the 12v system to allow the fridge to run on propane after the trailer shop rewired the camper. But from the responses, I am assuming that this is not going to be an issue.
 

Attachments

  • hopkins breakaway system.jpg
    hopkins breakaway system.jpg
    227.2 KB · Views: 12

Edd505

Well-known member
Joined
Mar 22, 2021
Posts
241
Location
Elephant Butte, NM
The break away will not work w/o a 12v supply. You said they fixed wiring to make the brakes work. Just what did the fix you may have ad a bad wire to one of the brakes or a short where the wire traverses inside the axle. Common wear point where it comes out of the axle. You sure the battery's for the brakaway only? Never heard of one wired that way. Your furnace needs 12V to work so there's a second battery for it?
 
Top Bottom