Dometic DMC 4101 Electric Only Refrigerator

[jranck]

So we are considering replacing our absorption fridge with an (electric only) DMC 4101. We have a 2018 flying cloud 25 FBT.

So has anyone put in an electric only fridge? Like? No like?

[richard5933]

There have been about half a dozen threads about this issue in the past few months, mostly about the all-electric fridges going into the newer models. Might be a good idea to do a search on the forum and read through some of those threads.

[jranck]

Originally Posted by richard5933

There have been about half a dozen threads about this issue in the past few months, mostly about the all-electric fridges going into the newer models. Might be a good idea to do a search on the forum and read through some of those threads.

I had done a search and found some threads about various repairs on the new rigs with the all-electric fridges, but hadn't found any that talked about pro/con experiences vs. absorption fridges. Maybe my search-fu isn't good.

[uncle_bob]

Hi

Quick summary:

Absorption fridges pull less 12V power. Better than compressor by maybe by 2:1, could be by 5:1. That's a lot of battery.

Compressor fridge cools down *much* faster. Holds temperature very well.

Compressor fridge is bigger inside for a given outer volume.

Absorption fridges are going away ( factory is shutting down / future production likely will be outlawed ....). Pretty much every RV manufacturer has dropped them. AS has held up doing this way longer than most.

Both require venting. The "how" is a bit different for each type.

Some compressor fridges are better than other efficiency wise. It's best to do your homework before buying this or that one. They have improved a lot over the years.

If you run in an area that outlaws "propane in motion" ( a few areas in the US, many more in Europe ) the ice cream will not melt with a compressor fridge. Even without laws, some folks really freak out about propane and feel the need to shut things off much of the time. That does not work well for the ice cream either.

You can get larger compressor fridges in dual compressor versions. This lets you control the freezer section separately from the refrigerator section. If really cold ice cream is what you are after (without freezing the milk), this is a plus. It is abundantly unclear if you pay a power penalty for this feature.

Bob

[n2916s]

Most of the folks who object to compressor fridges are those who prefer to boondock rather than stay in places with electric service. They have a point — the increased power demand requires a generator or a very capable solar installation (probably including Lithium Ion batteries)

If, like me, you are usually in a state or county park with power available, then a compressor fridge is probably an upgrade. If you are hoarding every amp hour while out in the boonies, not so much.

[OrangeCrush]

Data I have seen is the DC compressor fridge in new Airstreams use on average about 2.5Amps/hour. That would chew up 60AH of your batteries over 24 hour period. If that is a significant part of your battery bank and you like to boondock then you may be disappointed. Are you thinking about replacing it for a reason?

[jranck]

Originally Posted by OrangeCrush

Data I have seen is the DC compressor fridge in new Airstreams use on average about 2.5Amps/hour. That would chew up 60AH of your batteries over 24 hour period. If that is a significant part of your battery bank and you like to boondock then you may be disappointed. Are you thinking about replacing it for a reason?

Our absorption fridge works so so and we've had issues when we boondock in hot areas (we are in UT and boondock in a lot of hot places). I don't worry too much about the propane in motion, although it is something I think about. We have a pretty good lithium battery bank and are planning on a solar install to help keep things charged, and as part of the project I've been noodling on a 12V fridge.

Honestly, I think that we'd be fine for a few years at least with our absorption fridge, but I'm starting to do some thinking about a switch.

[jranck]

Originally Posted by uncle_bob

. . .

If you run in an area that outlaws "propane in motion" (a few areas in the US, many more in Europe) the ice cream will not melt with a compressor fridge. . . .

Bob

Hi Bob:

I've tried to find out where it is illegal in the US to tow with a propane fridge lit and haven't had great success. Any references where you shouldn't tow with a lit fridge?

Jeff.

[Mx468]

Here's the fridge I just put in my 72 Safari, so far, so good. Ice cold. I also have 400 watts of solar on my roof and another 120 watts in a portable suitcase and about 300ah lithium batteries. When connected to shore power I'm on 110/120 and while traveling down the road or boondocking I'm using 12v.

[field & stream]

Originally Posted by OrangeCrush

Data I have seen is the DC compressor fridge in new Airstreams use on average about 2.5Amps/hour. That would chew up 60AH of your batteries over 24 hour period. If that is a significant part of your battery bank and you like to boondock then you may be disappointed. Are you thinking about replacing it for a reason?

60Ah per day is a reasonable estimate for an electric only compressor fridge. That assumes about a 50% duty cycle — in practice it may be more or a bit less.

I have a 3 cu ft Dometic absorption fridge in my 16’ Airstream and measured by a Victron 712 it uses .3 amps per hour. That is only 7 Ah per day, or about 10% of the 60Ah referenced above. With a single 100Ah lithium battery I can run unplugged for 1-2 weeks without any recharging.

Unfortunately, there is a lot of questionable “data” out there on this issue. (Some Forum members report that their salesman represented to them that the compressor fridges use less electricity than absorption fridges!).

[field & stream]

Originally Posted by jranck

Our absorption fridge works so so and we've had issues when we boondock in hot areas (we are in UT and boondock in a lot of hot places). I don't worry too much about the propane in motion, although it is something I think about. We have a pretty good lithium battery bank and are planning on a solar install to help keep things charged, and as part of the project I've been noodling on a 12V fridge.

Honestly, I think that we'd be fine for a few years at least with our absorption fridge, but I'm starting to do some thinking about a switch.

With enough solar (400w min.) and enough sun (which you are likely to have) a compressor fridge could be a good move for you. Because of the benefits I seriously considered it, but don’t have enough real estate on the roof of my 16’.

[richard5933]

Originally Posted by jranck

Hi Bob:

I've tried to find out where it is illegal in the US to tow with a propane fridge lit and haven't had great success. Any references where you shouldn't tow with a lit fridge?

Jeff.

Other than possibly a few tunnels or in a gas station while fueling you probably will not find any restrictions.

[uncle_bob]

Originally Posted by richard5933

Other than possibly a few tunnels or in a gas station while fueling you probably will not find any restrictions.

Hi

Multiple routes with tunnels on them and no (rational) place to pull over to shut things down. Some areas allegedly have rules about shutting down anyplace that fuel is involved. That would include things like rest stops. Again a bit of a PIA if you actually know that's the rule and follow it. Lots of posts from folks here and there about this or that rule and not a lot of time to track them all down to the locality and it's (likely paper) records.

Bob

[uncle_bob]

Originally Posted by field & stream

60Ah per day is a reasonable estimate for an electric only compressor fridge. That assumes about a 50% duty cycle — in practice it may be more or a bit less.

I have a 3 cu ft Dometic absorption fridge in my 16’ Airstream and measured by a Victron 712 it uses .3 amps per hour. That is only 7 Ah per day, or about 10% of the 60Ah referenced above. With a single 100Ah lithium battery I can run unplugged for 1-2 weeks without any recharging.

Unfortunately, there is a lot of questionable “data” out there on this issue. (Some Forum members report that their salesman represented to them that the compressor fridges use less electricity than absorption fridges!).

Hi

Indeed, my absorption fridge on the Classic runs in the 1 to 1.2A per hour range as measured with the Smart Shunt. A compressor fridge that pulls 0.7A average would indeed be pulling less than my example of a great big absorption fridge.

The published data from some fridge makers is very unclear. They toss up a number that is labeled "average consumption". They then put a footnote on that number. That leads you off to a paragraph or six about how the number does not include millisecond wide pulses that may occur. Otherwise it's a full up running number and not an average at all. They then state that to get the number you need you take their number and multiply by your compressor run time percentage.

Yes, even that summary is confusing.

Bottom line: There isn't much good data out there on what the compressor fridges really do pull.

Bob

[richard5933]

Originally Posted by uncle_bob

Hi



Multiple routes with tunnels on them and no (rational) place to pull over to shut things down. Some areas allegedly have rules about shutting down anyplace that fuel is involved. That would include things like rest stops. Again a bit of a PIA if you actually know that's the rule and follow it. Lots of posts from folks here and there about this or that rule and not a lot of time to track them all down to the locality and it's (likely paper) records.



Bob

I researched this a couple of years ago and found very few tunnels with restrictions on propane transportation in tanks the size most RVs carry. Also found very few with restrictions on running a propane fridge while underway.

Do you have any data to share about places with published restrictions.

[OrangeCrush]

Originally Posted by field & stream

(Some Forum members report that their salesman represented to them that the compressor fridges use less electricity than absorption fridges!).

Yes, there is a lot of "fud" in this data point. There is some people who have tested the amount of electricity a compressor fridge uses and compared it to the amount of electricity an absorption fridge uses WHILE RUNNING ON A/C. With that data they declare "Voila", compressor fridge uses much less electricity than an absorption fridge. There is no propane in the test and it gives a data point salesmen can use to advertise a false advantage.

[n2916s]

The tunnel between Hampton Roads and Norfolk, Virginia has a checkpoint — you pull in and they check that your tanks are shut off. The Chesapeake Bay Bridge Tunnel also requires propane be shut off.

The only other place I’ve been that requires propane to be secured are the North Carolina State Ferries connecting the Outer Banks.

It is not much of an issue if it is only for an hour or so. Just don’t open the reefer until you can get it fired up again and cooling.

[Silvr_Bullet]

Originally Posted by field & stream

60Ah per day is a reasonable estimate for an electric only compressor fridge. That assumes about a 50% duty cycle — in practice it may be more or a bit less.

I have a 3 cu ft Dometic absorption fridge in my 16’ Airstream and measured by a Victron 712 it uses .3 amps per hour. That is only 7 Ah per day, or about 10% of the 60Ah referenced above. With a single 100Ah lithium battery I can run unplugged for 1-2 weeks without any recharging.

Unfortunately, there is a lot of questionable “data” out there on this issue. (Some Forum members report that their salesman represented to them that the compressor fridges use less electricity than absorption fridges!).

Question, when you cite .3 amp hours use per hour, is that an average hourly over a 24 hour period? If not how did you arrive at that usage. I have similar setup and am wondering how you partitioned out that .3 hour usage? Thanks

[dsatwork]

According to Marc at Keep Your Day Dream, who has two of these now one in his Airstream and one in his BlueBird Wanderlodge. I confirmed via email and has made the same assertion on his latest video "BlueBird Wanderlodge RV Tour: Pros & Cons" linked below, the Dometic 4101 uses about 50 watts an hour.

That's 600 watt hours or approximately 50 AH per day. 600/12=50AH

https://www.youtube.com/watch?v=6qvhmgy7rAE

I too am considering the Dometic 4101 but I have 500AH Battle Born Battery bank and 400 watts of solar on the roof and 400 watts of ground deploy which I plan to test thoroughly before making the change.

[field & stream]

Originally Posted by Silvr_Bullet

Question, when you cite .3 amp hours use per hour, is that an average hourly over a 24 hour period? If not how did you arrive at that usage. I have similar setup and am wondering how you partitioned out that .3 hour usage? Thanks

Good question. The electricity used by an absorption fridge is used by the control system only (not at all for the cooling process) so it is constant. The .3 amps was measured by the Victron 712 while the fridge was turned on, and confirmed by a 24 hour consumption of 7Ah. I have been watching this closely and the .3 never varies and I have tracked the 7Ah per day every time we go out, including a 10 consecutive day trip.

Note: this is a small (3 cu ft) fridge, and other Forum members have reported higher draws from larger absorption fridges. Since it is just a control board I don’t know why that would be the case, but I trust the reports.