Is the DC fridge mode used while in motion on the highway?

[Brimanzappa]

I found the installation instructions for this fridge (Dometic DM2683LBFX) but did not locate the user guide. I have confirmed the AC and propane modes work as they should. Is the DC mode used while in transit. Thanks for your input.

 

[Centex]

I found the installation instructions for this fridge (Dometic DM2683LBFX) but did not locate the user guide.

Attached, FYI.

You can use DC mode while in transit, but it's an "Amp Hog" (uses lots of DC power).

I prefer to use propane mode while in transit, shutting off the propane at the tank before approaching a gasoline-fill island and then restarting the fridge after I'm away from that potential explosive-fume environment.

YMMV.

 

[HABBERDABBER]

With a standard configured vehicle-to-trailer electrical set-up, you will likely deplete your trailer batteries before you get to where you're going. Like the above post, propane is your best option, without doing significant electrical wiring/alternator upgrade modifications to your vehicle.
That's not been worth doing all that stuff for my use and travels.
YMMV

 

[Brimanzappa]

Thanks for the replies. I'll be using propane.

 

[GinoandLinda]

Propane is your best bet. There are some precautions you should take when fueling the tow vehicle since the fridge operating on propane is considered an open flame. All you need to do is turn your fridge off before approaching the pumps. Also some tunnels do not allow operating propane appliances when driving through.

 

[Brimanzappa]

Is there any practical use for the DC mode?

 

[Centex]

I've only run mine briefly in DC mode once, just a test to see that it worked and wasn't at all efficient.

 

[Rossue2]

....and FYI- most USA built RV's have 2-way refrigerators; so DC mode isn't an option. Like others here I have tried DC mode and it isn't useful to us.

 

[GinoandLinda]

....and FYI- most USA built RV's have 2-way refrigerators; so DC mode isn't an option. Like others here I have tried DC mode and it isn't useful to us.

So, 2-way fridges are a different animal from a 3-way. 2-ways use a compressor which is far more efficient than the heated ammonia system on a 3-way were a heating element is involved instead of a compressor. As long as you have a good supply of 12v power through a large capacity battery bank and/or plenty of solar power, a 2-way running on DC is effective and efficient. Still, some of us prefer having the three options of AC, DC and propane and lament the demise of the 3-way fridge.

 

[Jeremy Kessenich]

So, 2-way fridges are a different animal from a 3-way. 2-ways use a compressor which is far more efficient than the heated ammonia system on a 3-way were a heating element is involved instead of a compressor.

This is off the ETI web page:

 

[GinoandLinda]

This is off the ETI web page:

View attachment 1107706

Awesome! I was unaware of this. I have renewed hope. Thanks.

 

[Viajante]

I did find out about a useful aspect of DC mode. When plugged into shore power I noticed that my Dometic 2354 3-way had switched over and was running on DC. Which was ok because the power was coming from the converter, not the battery.

It turns out the 110v selector circuit had failed. Because the fridge sensed 110v power it did not default to propane, but it was unable to cool on 110v. In that case (plugged into shore power) it defaults to DC. Or, the user can manually switch to propane.

Troubleshooting with a multi meter was quick. The fix was a new control board.

This may not be a common problem but it is a case where DC performs a good backup function without draining the battery.

 

[Rossue2]

2-way, as references above are absorption-not compressor. They are exactly like a 3-way sans DC mode.

I had an issue when I replaced my 3-way RMD8555 with another 3-way Dometic model that is a direct replacement- the RMD10.5XT. I called a mobile tech well known and with good reviews. He didn't want to take on the job saying 3-way refrigerators are too complex. Another shop that Dometic referred me to wanted to pull the whole unit out to "run it through it's paces" for $500 up front. That was a violation of Dometic's policy for warranty work, yet they wouldn't budge.

It turned out to be a stupid operator error with control differences between the two models. The 10.5XT being made primarily for the Eurooean market has a default to DC and when you change modes it has to be then confirmed or it will just revert back to the prior mode. Doh!

The point is again: the vast majority of RV refrigerators in the US are 2-way and due to this most techs have little to no experience working on any DC issue and many tend to not want to bother at all when they are so busy fixing the ones they are familiar with.

One time I did use the

So, 2-way fridges are a different animal from a 3-way. 2-ways use a compressor which is far more efficient than the heated ammonia system on a 3-way were a heating element is involved instead of a compressor. As long as you have a good supply of 12v power through a large capacity battery bank and/or plenty of solar power, a 2-way running on DC is effective and efficient. Still, some of us prefer having the three options of AC, DC and propane and lament the demise of the 3-way fridge.

DC operation and forgot to switch it back to propane after arriving at camp. Not good- it drained the house 12V batteries and the alarm sounded at 4 AM of course!

 

[Selkirk]

I have the Dometic 5.0cuft 3way absorption fridge in my E19. I fully understand that its current draw is very high while operating in DC mode.

Not to open the propane debate, but my self-imposed rule is to tow with the tanks turned off. I normally travel with the fridge shut down and a couple of large cold packs tossed in the compartment (turning the fridge into a big cooler). I don't open the fridge while travelling unless absolutely necessary. So far this approach has worked for me.

My trailer's electrical system is factory configured with 2x190 w solar panels, Victron MPPT charge controller, 2x6v LA batteries, and a 12V-12V DC charger.

Assuming I travel in the daytime and under generally sunny conditions....I've always been curious if I have enough charging capacity between the TV charge line and Solar to offset the high current draw if I towed with the Fridge in DC mode.

I guess there is only one way to find out......

 

[brroberts]

Depending on the wiring and the DC charger plus two solar panels, maybe. I’d find out. I run on propane, but in the future hope to be set up similar, but with a larger battery bank to run 12V.

 

[GinoandLinda]

Depending on the wiring and the DC charger plus two solar panels, maybe. I’d find out. I run on propane, but in the future hope to be set up similar, but with a larger battery bank to run 12V.

We tried running our 3-way on DC while traveling and the battery capacity could not keep up. Our setup is 400ah lithium battery bank, 380 watts of solar up top and DC-DC charger with a '22 F150 tow vehicle. If I remember correctly, we drove better part of the day with mostly sun. The batteries were at 100% when we left and were at 85% when we arrived at our campsite. It was a hot day, however.

 

[Ron in BC]

Not to open the propane debate, but my self-imposed rule is to tow with the tanks turned off.

Good grief, don't do that because then I might mention that my fridge runs on propane from the minute I leave home until I return. Except if I have to shut it down for a ferry or tunnel. Well, being cheap, if there's 110V available and I've paid for it, I'll use it.

If I had a van type RV I'd shut it down refueling but I don't consider the trailer, well outside the gas pump area, a hazard.

Ron

 

[dosby]

Our 3 cu ft in 17B consumes ~10A in DC mode, i.e. ~120W. Ok on the highway, where solar is unobstructed and charging, and vehicle is also charging at least 10A DC-DC. Ok for 1-3 hr ferries. Otherwise, run on gas. It works even better b/c of constant shaking of the internal tubing.

 

[alanmalk]

My tow vehicle (Tacoma) could not supply enough power through its undersized wires to keep up with the Dometic RMD8555 in 12VDC mode, as installed by Escape. Therefore the batteries would be supplying all the power while driving**. But, if by chance you have a double solar panel on the roof and a sunny drive, you probably would be fine. Another option would be a fairly large ($$) DC-DC converter to overcome the voltage loss between alternator and battery.

** I measured a 1.5 V drop between alternator and trailer batteries in a 'fridge load test. That convinced me to use propane while driving.

 

[dosby]

I do have DC-DC converter (Orion), it connects via blutooth for monitoring. I also have Victron shunt/monitor. So I measured the draw exactly, it was 10A from the fridge. And the Orion was charging only 10A.
Solar is hit or miss, but normally 5-10A on the highway during daytime. I have one 180W panel.
Obviously, I only use DC for testing the draw, on ferries, and whenever I have enough power, just to save propane. Just one panel can't keep up powering the fridge even in full sun, but I can last a day or so on my 300A battery.