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03-22-2021, 03:39 PM
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#1
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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12v Dometic Fridge Test In MM 2108DS
I’m doing a real world performance test on my 12v only Dometic Fridge. Lots of folks, including me want to know how long you can boondock with this fridge.
I started this test at 4:30pm EST. So, I will report test results here tomorrow.
Equipment used in this test:
170ah LiFePo4 Battery
Xantrex XC 2000w Inverter/Charger
Victron Smart Shunt
To simulate real world results:
Fridge pre-chilled for 24 hrs.
One bag of ice in freezer to simulate frozen food thermal mass
Refrigerator empty
Incipient (phantom) dc loads not disconnected
This includes, alarms and sensors, stereo, tv and Roku all off, but drawing small current in standby
Xantrex left on in standby with no AC loads on, except as stated above.
Ambient outdoor temperature 64F
Beginning SOC 100%
Shore power disconnected
The actual amp hour consumption of the fridge will be something less than what the Victron reports, but it will approximate 24hr consumption. If anybody is interested in me repeating this test with the Xantrex disconnected, please let me know.
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Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-22-2021, 04:42 PM
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#2
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Site Team
Join Date: Sep 2009
Location: Spring Branch, TX
Posts: 7,868
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Since the fridge doesn't run on 120v AC why would you leave the Xantrex inverter on? Even in standby it uses some of your 12v power. You'd think you would want to find out how much 12v the fridge - alone - uses, not how much the fridge and your inverter use together.
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2017 Winnebago Adventurer 37F
2016 Lincoln MKX Toad
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03-22-2021, 05:05 PM
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#3
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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Correct Creative.,
First test, I’m attempting to simulate real world. In real world we will not shut down the inverter. That gives us the real measure of boondocking time.
I think I should do another test with inverter disconnected, which would give a much closer measurement of ah used by fridge.
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Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-22-2021, 05:25 PM
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#4
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Winnebago Master
Join Date: Feb 2020
Posts: 887
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Are you living in it overnight with lights, device charging, water pump, water heater controls, etc. all running? If so fine, but as creativepart notes, it is not a measure of how much the fridge draws.
David
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03-22-2021, 05:48 PM
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#5
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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Quote:
Originally Posted by DavidM
Are you living in it overnight with lights, device charging, water pump, water heater controls, etc. all running? If so fine, but as creativepart notes, it is not a measure of how much the fridge draws.
David
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No, not living in it for this test. Although, when we are living in it, I turn off water pump, water heater, etc. overnight, and back on in the morning. When we boondock, all AC loads are off, and standby DC loads are off.
The second test with inverter disconnected will be as accurate a measurement of fridge consumption as you can get. I’ll start the second test tomorrow at 4:30pm by just turning off the inverter disconnect. That will remove all AC incipient loads. I’ll report SOC at the beginning of second test, and at end 24 hours later. I don’t think it’s necessary to disconnect dc incipient loads at the breaker panel, as you can just deduce their watt hours and add them back into the observed amp hour consumption if you like.
I really don’t think we’ll see much difference in the measurements. I’m guessing maybe 3-5 ah over 24 hrs.
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Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-29-2021, 12:51 PM
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#6
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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Final Dometic 12v Fridge Test
Testing to determine how many days I can boondock using the 12v only Dometic fridge that came standard with our 2021B 2108DS.
Equipment: 170AH LifFePo4 battery, Xantrex XC2000 inverter Charger, Victron Smart Shunt Battery Monitor. Shore Power is disconnected during test phases.
Incipient or phantom loads (sensors and alarms) were left connected in both phases. They measure .25A, so over each 24 hr phase, 6AH should be subtracted from actual fridge consumption
Two phases
Average daytime temperature 65 F
Fridge pre-cooled for 24 hrs
Two trays of ice in freezer to simulate thermal mass
Otherwise, freezer and fridge empty
Shore power disconnected at start of each phase
Battery recharged between each phase so SOC starts at 100%
Phase 1: Xantrex in Standby mode. All AC and DC loads except fridge and incipient off
Starting SOC 100% Voltage 13.24
Ending SOC 75%. Voltage 13.0
Consumed 41.9AH
Phase 2: Xantrex disconnected. All DC loads except fridge and incipient off.
Starting SOC 100% Voltage 13.01
Ending SOC 82% Voltage 12.93
Consumed 30.5AH
Bottom Line:
If you have this fridge and consume normal additional DC power daily, AND leave your inverter disconnected, you will need approximately 50AH of useable battery bank for each day of boondocking. With my setup, I can comfortably boondock for 3 days before I need to start my generator to recharge battery. So, I’m pleased that our big Dometic compressor fridge consumes less than 25AH per day.
Hope you all find this info useful.
__________________
Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-29-2021, 02:49 PM
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#7
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Winnebago Master
Join Date: Jul 2020
Location: Land of calenture (TX)
Posts: 679
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That’s incredible. I would have thought the average amp draw would be much higher. It’ll be interesting to see how it changes with usage and higher ambient temps.
My absorption fridge + phantom was between 0.8 amps (fan off) and 1.2 amps (fan on) when I measured it the other day while running on propane.
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The most insidious lies are the ones we really want to believe - please avoid partisan news.
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03-29-2021, 05:43 PM
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#8
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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Yeah,
I think the numbers will be significantly higher with ambient temperatures at 80F and above. But surprised that this fridge doesn’t use much more power than an absorption on propane. Probably less than an absorption on 12v. I was also shocked at the amount of AH consumed by the Xantrex in standby. OMG. No loads, and it sits there with it’s own deep fryer going.
__________________
Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-29-2021, 06:36 PM
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#9
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Winnie-Wise
Join Date: Apr 2017
Location: South Central, Pennsylvania
Posts: 446
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Jim, thanks for the 12V fridge AH info.
Fred
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2016 Winnebago Micro Minnie 2106DS, 200Ah BB, 400w rooftop & 500w front cap solar
2020 Tundra SR5 DLCB TRD Off Road, 5.7L V8 w/6.5' bed & 38 gal. tank, 4.30 axle ratio
Blue Ox Sway Pro w/750# bars, wired RVS rear view camera, Renogy 20A DC/DC charger
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03-30-2021, 05:57 AM
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#10
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Winnie-Wise
Join Date: Dec 2020
Location: Upstate SC
Posts: 303
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Thanks for the analysis Jim. Good info!
How much do you think the numbers would change with:
1. Fridge/freezer in various states of volume (food contents)
2. Opening/closing the doors multiple times, including leaving it open ~15sec.
Just thinking that this could potentially increase consumption.
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2020b Micro Minnie 2108TB / 2022 F-150 Super Crew 4X4
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03-30-2021, 06:14 AM
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#11
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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Hi Rock,
The more food you put in the fridge and freezer (as long it’s cold when you put it in fridge and frozen for freezer), the more thermal mass there will be; so the consumed amperage should be less. Conversely, If you fill the freezer with unfrozen food, and the fridge with room temperature items, consumption will be substantially higher, as the compressor has to stay on for a long time to chill that stuff. So, it’s much better if you load the fridge the day before leaving.
I’m just guessing about opening and closing doors, but the Victron reports 6amp draw when the compressor is on. And as I just reported, only 1 amp draw during the test. So, if the compressor comes on for 3 minutes every time you open the door, you can probably extrapolate an estimate of how many additional AH will be used.
__________________
Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-30-2021, 08:05 AM
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#12
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Winnebago Master
Join Date: Oct 2018
Location: Apache Junction, AZ
Posts: 1,244
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Quote:
Originally Posted by Marine359
If you have this fridge and consume normal additional DC power daily, AND leave your inverter disconnected, you will need approximately 50AH of useable battery bank for each day of boondocking.
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We have the Dometic DC0061 12 volt compressor refrigerator in our 2018 Fuse and I have now had more than 2 years to see how much electric it uses. We boondock most of the time and I have noticed how much power it consumes from our 200AH of BB Lithium batteries, in both Winter and Summer, so perhaps I can contribute some real life experience to this thread.
What I have found is the obvious - the refrigerator uses about twice the power in the Summer as in the Winter and is sensitive to how much the sun is heating any outside surface near the refrigerator. When the sun is on the side of the RV with the fridge I put out the awning to keep the side as cool as possible to reduce battery usage.
During Winter the refrigerator consumes about 30AH (15% as measured by our BM) from 7pm to 7 am, and about the same during the day for a total of about 60AH.
During the Summer this jumps to about 50AH (25% as measured by our BM) during the same 12 hours and a bit more during the day, for a total of perhaps 120-140AH. Of course this is Arizona and the summers tend to be hot, even in the mountains, due to the intensity of the sun so this figure would be less in a less harsh climate.
We have 400 watts of solar and in the Winter we can boondock for 3-4 days before our power gets too low and we have to run the generator. It would be longer but the sun is too low in the sky for us to get more than perhaps 30-40AH of power and we also use a fair number of small, but power hungry, appliances like my wife's electric tea kettle and toaster as well as the TV and DVD player, some electric fans and some other stuff.
In the Winter we can only boondock for perhaps 2 days before I have to run the generator. We get a lot more solar (perhaps 120AH as measured by the Zamp solar controller) but we use all of that and more for just the refrigerator.
And since the Zamp solar controller is a PSW it is probably not actually applying all of the solar that the panels generate since it is only using about 14 volts of the 18-19 volts that it gets. I could probably extend the boondocking time by installing an MPPT solar controller but have not as of yet.
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2020 Regency Ultra Brougham, IB model
2022 Jeep Wrangler Sport S toad
Roadmaster baseplate and tow bar
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03-30-2021, 08:28 AM
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#13
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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AJ,
I was wondering why your numbers and mine are so far off. Seems you actually have the Norcold DC-0061, not the New Dometic DMC4101, which is being installed in all new Micro Mini builds (since mid-year 2020). Just checked the forum, and understand some owners with the Norcold are replacing their Norcold fridge with the new Dometic I don’t know long term real world will be for the DMC4101, but I’m guessing it’ll come in around 35-40AH per 24 hour period in warmer climates. Thanks for the great tips on getting the best efficiency from a compressor fridge.
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Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-30-2021, 08:42 AM
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#14
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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__________________
Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-30-2021, 09:35 AM
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#15
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Winnebago Master
Join Date: Oct 2018
Location: Apache Junction, AZ
Posts: 1,244
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Quote:
Originally Posted by Marine359
AJ,
I was wondering why your numbers and mine are so far off.
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I think for several reasons.
First, the Winter and Summer sun here in Arizona is very strong and easily heats up the skin of our Fuse, and the refrigerator is fairly close to the outside of the RV and thus probably absorbs some of the heat regardless of whether or not the awning is out.
Next, my wife is constantly opening and closing the refrigerator door and I have a hard time impressing on her the importance of closing it quickly. Thus the outside heat is getting inside and forcing the compressor to work more than otherwise.
Also, we don't use the water in our fresh water tank for drinking, but bring drinking water along with us. As that is used up my wife fills the bottles with more fresh water which is sometimes warm and thus that adds to the need for the refrigerator to cool it down.
And in the Summer in the mountains it is hot. The nights may be 70-75 but the days are well into the 90s and I have to set the fridge on 5 (the max) on its setting to keep the freezer well below freezing. Add to that use of the DVD player and the TV, the electric tea kettle, the toaster and the fans and sometimes we go to sleep with the batteries at 90% (100% at sundown, but down to 90% at bed time) and wake up in the morning with them down to 55-60%. 30% usage overnight means 60AH in 12 hours which translates to 5 amps per hour, or nearly a nearly constantly running refrigerator.
BTW - my numbers on general usage are about the same as yours. 5 amps per hour for the compressor fridge when running and 1 amp per hour for the general background stuff. For us you need to add the electric fans we run at night, the electric tea kettle (and toaster when it is used) that we use for breakfast, lunch and dinner and the TV and DVD player. Plus whatever extra we use. The Lithium batteries we added have freed us up to act normally when we are dry camping.
Quote:
Originally Posted by Marine359
AJ,
Seems you actually have the Norcold DC-0061, not the New Dometic DMC4101, which is being installed in all new Micro Mini builds (since mid-year 2020). Just checked the forum, and understand some owners with the Norcold are replacing their Norcold fridge with the new Dometic
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I believe that Dometic and Norcold are the same company with each being a separate division. I have seen the DC0061 being advertised as both a Dometic DC0061 and a Norcold DC0061 and I assume both are identical with different labels.
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2020 Regency Ultra Brougham, IB model
2022 Jeep Wrangler Sport S toad
Roadmaster baseplate and tow bar
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03-30-2021, 09:37 AM
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#16
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Winnebago Master
Join Date: Jul 2020
Location: Land of calenture (TX)
Posts: 679
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Quote:
Originally Posted by Marine359
Hi Rock,
The more food you put in the fridge and freezer (as long it’s cold when you put it in fridge and frozen for freezer), the more thermal mass there will be; so the consumed amperage should be less.
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I'm really curious about this. At best, I think it would be about the same amperage.
If you're still in a mood to do experiments, it might be fun to do this one more time (inverter off maybe) but start off with jugs of water in the fridge and maybe a few bags of frozen peas (or whatever) in the freezer to stand-in for the typical mass of contents.
Regardless, I appreciate the effort you've already put into this and the fact that you shared it with us here.
Edit: I should add that the numbers I mentioned above were simple instantaneous readings with the fridge actively cooling. I don't have a shunt-style monitor yet so I can't do the integration and report average consumption. I've read on other forums that 0.8-amps is pretty typical for the absorption units when running on propane.
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The most insidious lies are the ones we really want to believe - please avoid partisan news.
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03-30-2021, 09:50 AM
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#17
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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My TGW (the great wife), wanted this new RV, but only on the condition she could glamp with all the comforts of home. So my real world consumption is likely to be similar to AJ’s. Florida trip next month, so no boondocking, except Cracker Barrel. When we boondock for longer periods, likely we’ll run the gennie every day for an hour or more. Also likely that I’ll put 200w panel on the roof this summer.
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Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-30-2021, 10:05 AM
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#18
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Winnebago Owner
Join Date: Oct 2020
Location: Asheville, NC
Posts: 1,674
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Quote:
Originally Posted by AJMike
I believe that Dometic and Norcold are the same company with each being a separate division. I have seen the DC0061 being advertised as both a Dometic DC0061 and a Norcold DC0061 and I assume both are identical with different labels.
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Since 1997, Norcold a subsidiary of Thetford, which is owned by another company I’ve never heard of. But definitely not related to Dometic, a Swedish company. Dometic and Norcold fridges not built in same factory. https://www.vault.com/company-profil...ts/norcold-inc
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Jim. Former, 2021b Micro Minnie 2108DS
Medically grounded, but still lurking the Micro Minnie Discussions
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03-30-2021, 10:10 AM
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#19
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Winnebago Master
Join Date: Oct 2018
Location: Apache Junction, AZ
Posts: 1,244
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Quote:
Originally Posted by Marine359
Since 1997, Norcold a subsidiary of Thetford, which is owned by another company I’ve never heard of. But definitely not related to Dometic, a Swedish company. Dometic and Norcold fridges not built in same factory. https://www.vault.com/company-profil...ts/norcold-inc
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I guess I need to go back to the RV and pull out the documentation for the refrigerator. I was sure that it was listed as a Dometic but perhaps that is wrong and it is after all a Norcold. If so, my mistake and I apologize.
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2020 Regency Ultra Brougham, IB model
2022 Jeep Wrangler Sport S toad
Roadmaster baseplate and tow bar
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