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Trogdog 09-09-2012 06:17 PM

Fridge drains battery...
I have a Rockwood A122 A-frame with a dometic fridge. The fridge seems to be draining my battery while on the road (we typically drive 4 to 6 hours away from home and keep the fridge on DC power while driving). Do other folks have a similar issue, or is there a problem with my rig? Since I'm fairly new to this, is it ok to use the propane while driving to keep the fridge cool rather than the DC to save battery power?

Terier 09-09-2012 06:19 PM

There is some debate with using propane while traveling. I do travel with the propane on to keep the fridge cold.

TURBS 09-09-2012 06:53 PM

I have traveled for years with propane on.

Twisty 09-09-2012 06:58 PM

I would say that there is a problem with the 7 pin plug or wiring. For some reason, power is not getting from the TV to the battery and keeping it charged.
I have to travel with propane on or the fridge will be off. I have a 2 way fridge.

OldCoot 09-09-2012 07:15 PM

We had a 3 way frig in a 72 El Camino slide in and we could run the frig on 12 while traveling, but it would run 2 batteries dead if left on for over 2 hrs. Would even turn it off when we went into a restaurant for lunch, etc.

Road-King 09-09-2012 08:11 PM


Originally Posted by f1100turbo (Post 249614)
I have traveled for years with propane on.

X2... No problems...

dbuzz77 09-09-2012 08:28 PM

yes, i would check your charging lead from the tv.

Trogdog 09-09-2012 08:45 PM

Thanks for all the replies! I had to think for a moment before I realized TV meant tow vehicle and not television! I think the charging line is working ok, I left the fridge off during the drive home and it seemed to charge ok. I'll try driving with the propane on next time and see how it goes.

bob213 09-09-2012 09:11 PM

I had at leat 20 warning stickers on my new trailer when I got it. Not a single one about using the propane while driving. It's designed with that in mind. If you want to be extra careful, turn it off at the gas station while you refuel and some tunnels require it to be off before you enter. Other than that, go for it!

KyDan 09-10-2012 06:37 AM

We ran a poll here awhile back asking simply "do you travel with your
fridge on LP or not".
80% of the poll responders said yes.

You can read some discussion here--

This question comes up often and there are many other threads about it.

We used to have a trailer with a 3 way fridge as you apparently do.
I also found I arrived at my destination with less than a full trailer
battery if I had the fridge on DC operation.
We switched to running with LP on and problem solved.
Now days, very few fridges come with 3 way power and I believe it's cost
saving plus the huge battery drain that's the reason.

Happy Camping!!

chucker25 09-10-2012 07:04 AM

1 Attachment(s)
Trogdog - I have an A128S A-frame so it would be the same fridge you have I would think. In my tests the fridge draws a very solid 10amps when running on 12volts. The 12volt line coming back from the tv should keep the battery up while travelling when the fridge is on 12volt, so I don't need to make the decision of whether to keep propane open when travelling, and the fridge is as cold as when it is run on 120vac. I think you should run some tests using a voltage meter to make sure your 12volt line does have power, and then to see if it is keeping the battery on the trailer charged.
First step is to test the 7way connector at back of the tv to ensure the 12volt connector has power (pin 4 on the attached diagram).
Then, with the tv NOT coupled to the trailer and the shore power disconnected let the fridge run on 12volts for a hour or 2, and check the trailer battery voltage every 15mins. You should see it slowly drop.
Then plug the tv into the trailer and start the tv engine - now when you check the trailers battery voltage it should be going up - slowly. This is the normal operation. If the trailer battery voltage doesn't rise then it sounds like there might be a wiring issue either at the 7-way connector itself, or in the wiring between the 7way and the trailer battery/trailer controller. Keep in mind the ground connections,just as important as the positive side of the equation. I suppose it might also be that the 12volt line providing power to the 7way from the front of the tv may be too small a gauge and can't handle the current draw, but lets hope that isn't the issue.
I can't stress enough the value of a small multi-tester. I picked up a unit that tests DC & AC voltage, DC & AC amps via inductive pickup and of course it has an ohms range for continuity tests. I keep it in the trailer at all times. great for testing battery condition when boondocking etc.

KyDan 09-10-2012 07:22 AM

Randy, I totally agree with you that everyone needs a meter and the
ability to use it for basic voltage tests and the occasional fuse check!

But I am absolutely sure my early trailer that did have a 3 way fridge was
correctly wired. I used to plug in my truck in order to get a little extra
boost if my trailer battery was getting low near the end of a weekend.

I know the alternator is supposed to charge the trailer battery thru the
7 pin plug but it typically doesn't do much.
The problem is the long distance between the engine battery and the
trailer battery and the under size wire in between.
This has been discussed here many times.
Search for "will my trailer battery charge while driving".

I know for a fact that my trailer battery was being slowly drained
by the fridge while on the road. If I left it on during a lunch stop the
truck would barely start when we were done! 10 amps draw is huge.
My advice is still run with LP on. If it works for you great but I had times
I wanted my trailer battery to be absolutely full when I arrived and that
would not happen if I had the fridge on DC operation.

TURBS 09-10-2012 07:46 AM

Maybe a dual battery set up is in order here.

lswartz 09-10-2012 08:02 AM


Originally Posted by f1100turbo (Post 249789)
Maybe a dual battery set up is in order here.

Agreed, I use 2 6 volt golf cart batteries. I would also only run it on propane or 110 volt as that costs a lot less that 2 new batteries. I need 2 6 volt batteries to dry camp for 7 days.

chucker25 09-10-2012 08:07 AM

Hi Dan

No doubt every scenario is different - be it the wiring runs, the charging ability of the tv, the fridge, the battery etc. The quick test I outlined will at least indicate if it will keep the battery up or not, and if not, and there are no obvious wiring issues then the decision can be made re using propane when travelling. My previous pup was not wired for the 12v line so I had no choice but to use propane as the battery would be drained - this new trailer/tv combination works great and I don't have to keep a propane tank open when on the I'm happy.

TURBS 09-10-2012 08:10 AM

I also have to wonder if the battery is in good condition ?
An ailing battery won't last long in that situation.

A good 24 hr 2 amp charge and a load test may be in order.

I have to wonder how old the battery is.

Tiggerdad 09-10-2012 08:29 AM

What is your tow vehicle? Some of the Chevy's need a fuse installed to charge the trailer battery. My 2006 D/A has a fuse installed from the factory. Friends 2006 did not

TURBS 09-10-2012 08:32 AM


Originally Posted by Tiggerdad
What is your tow vehicle? Some of the Chevy's need a fuse installed to charge the trailer battery. My 2006 D/A has a fuse installed from the factory. Friends 2006 did not

Some Ford's need a relay to work as well.

I guess and here I go again I assumed the charge circuit was known to be working.

Trogdog 09-11-2012 01:47 AM

Thanks. That makes me feel better about running with propane on.

Trogdog 09-11-2012 01:55 AM

TV is a 2008 Jeep Rubicon. Trailer battery was all but dead at the end of a two day camp trip. I left the fridge off on the way home, and by the time I got home five hours later the battery had enough juice to run both the lights and the fan. I'm guessing this means the charge line is hooked up?

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