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Old 08-29-2020, 01:20 PM   #1
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12V compressor refrigerator

My wife finally gave me permission to replace my 20 year old Dometic side x side with a new Dometic dmc4101, provided it was an exact fit with no trim mods, Then I measured the old RM7732 and found it is about 6" wider. (about 36" wide) . I have searched and can not find a 12v to replace what I have.
No, I do not want a residential fridge, yes I boondock a lot, and would not be thrilled doing the compressor conversion.
The 7732 has been on limp mode for a month and I can't get it out of it. 56 degrees on AC and 25 degrees on gas. Replaced the thermistor with a snip it kit.
Any thoughts or good ideas? No, the wife stays...

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Old 09-02-2020, 10:49 AM   #2
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Call Junior at JC Refrigeration and see it he makes a compressor-type cooling unit for your fridge! That's what I will be using if mine ever goes out again!
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Old 09-03-2020, 09:16 PM   #3
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on you degree info 25 vs 56 are you measuring the freezer or what?
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Old 09-04-2020, 09:32 AM   #4
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the 25/56 is refrigerator temp.
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Old 09-05-2020, 07:13 PM   #5
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on you degree info 25 vs 56 are you measuring the freezer or what?
Hard to understand getting the ref. section down to 25 degrees and if it is then the obvious answer is the electric heat strip must be failing. Maybe loose from the surface of the heater tube.
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Old 12-24-2020, 06:38 PM   #6
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Hello Azlandman, how is the DMC4101 holding up for you?

Did you have to upgrade your wiring?

Thanks

Bill
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Old 12-24-2020, 08:14 PM   #7
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I agree with Rkesselus. If your refrigerator gets down to 25 degrees on gas then the cooling unit works. That suggests a faulty electric heating element or circuit.
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Old 12-25-2020, 06:45 AM   #8
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Hello Azlandman, how is the DMC4101 holding up for you?

Did you have to upgrade your wiring?

Thanks

Bill
I wound up repairing the old Dometic. Until someone comes out with a compressor fridge closer in fit I'll stick with my 2 way in the National.
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Old 12-25-2020, 07:46 AM   #9
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Keep in mind regardless of the flavor of electrical power the fridge might use, 120VAC or 12VDC, the amount of energy the compressor is going to consume, measured in watts, isn't going to change much. From what I could find the Dometic DMC4101 operating off of 12VDC @ 13 Amps which works out to 156 Watts. My 10 cu ft Magic Chef residential demands 120VAC @ .97 Amps (measure via a Kill-A-Watt) which is 116 Watts. Even with the 10% power penalty of the invertor there is little if any advantage of a DC compressor over an AC power type.

Dometic hasn't published much in the way of power consumption of the variable speed compressor so I'm working off of third party information. You also need to consider cost at over $1000 for the 12VDC version. My Magic Chef was $350 from Home Depot and the pure sinewave 1000 watt inverter was an additional $250 off Amazon. $500+ will buy a lot of solar panel, fuel or camp sites.

https://www.rvtravel.com/dometic-new...or-run-fridge/
https://pantherrvproducts.com/dometi...reezer-10-c-f/

Any camper who spends most of there time off grid camper their best option might be to stick with an absorption type fridge by either repair, replacement of the cooling loop or complete replacement of what they currently have.
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Old 12-25-2020, 08:18 AM   #10
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Keep in mind regardless of the flavor of electrical power the fridge might use, 120VAC or 12VDC, the amount of energy the compressor is going to consume, measured in watts, isn't going to change much. From what I could find the Dometic DMC4101 operating off of 12VDC @ 13 Amps which works out to 156 Watts. My 10 cu ft Magic Chef residential demands 120VAC @ .97 Amps (measure via a Kill-A-Watt) which is 116 Watts. Even with the 10% power penalty of the invertor there is little if any advantage of a DC compressor over an AC power type.

Dometic hasn't published much in the way of power consumption of the variable speed compressor so I'm working off of third party information. You also need to consider cost at over $1000 for the 12VDC version. My Magic Chef was $350 from Home Depot and the pure sinewave 1000 watt inverter was an additional $250 off Amazon. $500+ will buy a lot of solar panel, fuel or camp sites.

https://www.rvtravel.com/dometic-new...or-run-fridge/
https://pantherrvproducts.com/dometi...reezer-10-c-f/

Any camper who spends most of there time off grid camper their best option might be to stick with an absorption type fridge by either repair, replacement of the cooling loop or complete replacement of what they currently have.
If you're comparing a residential fridge to an LP fridge being run on electrical power it's not a fair comparison. An LP fridge is designed to be most efficient running on LP, not electricity, and they will be power hogs on the cord.

My DC compressor fridge only consumes 5.7 amps when it operates, and it has about a 50% duty cycle. That is less than the approx. 10 amps your residential fridge consumes.

There are efficiency advantages to a DC compressor fridge. Whether one is the ideal solution for an individual depends on the intended usage. If extended run time from battery is the goal, then a DC compressor fridge is ideal. If the goal is to be able to run the fridge as you drive from pole to pole, then the residential unit is probably better.

I'd second the advice to check into the option of converting your existing fridge from LP to DC compressor using the kit from JC Refrigeration. They will also install the kit for you, and I'd suggest that as the ideal way to do this unless it's something you're comfortable with and are willing to assume the risk of an installation error causing malfunction.

I've read really good things from people who have installed these kits. No modification to the mounting or cabinetry will be necessary and it should meet the rules set by your wife.
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Old 12-25-2020, 08:40 AM   #11
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Originally Posted by richard5933 View Post
If you're comparing a residential fridge to an LP fridge being run on electrical power it's not a fair comparison. An LP fridge is designed to be most efficient running on LP, not electricity, and they will be power hogs on the cord.

My DC compressor fridge only consumes 5.7 amps when it operates, and it has about a 50% duty cycle. That is less than the approx. 10 amps your residential fridge consumes.

There are efficiency advantages to a DC compressor fridge. Whether one is the ideal solution for an individual depends on the intended usage. If extended run time from battery is the goal, then a DC compressor fridge is ideal. If the goal is to be able to run the fridge as you drive from pole to pole, then the residential unit is probably better.

I'd second the advice to check into the option of converting your existing fridge from LP to DC compressor using the kit from JC Refrigeration. They will also install the kit for you, and I'd suggest that as the ideal way to do this unless it's something you're comfortable with and are willing to assume the risk of an installation error causing malfunction.

I've read really good things from people who have installed these kits. No modification to the mounting or cabinetry will be necessary and it should meet the rules set by your wife.
What make, model, and size is your fridge?
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Old 12-25-2020, 12:20 PM   #12
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What make, model, and size is your fridge?
My fridge is a Vitrifrigo with just shy of 6 cu ft. Don't remember the model number. It uses basically the same Danfoss compressor as many other DC compressor units.

It's not as big as the residential mentioned above, but the guts in mine are also used for larger units that they sell. The only real difference would be a longer run time to initially bring it down to temp, as the compressor would still pull the same current while operating. A bigger box doesn't change the draw on the compressor just the run time.

These things are so well insulated though that it constantly impresses me with how quickly it cools down.

One mod I made to it was to add a second fan on the compressor unit which runs constantly when the unit is turned on. At less than 0.25 amps, I find it worth it since it helps reduce run time for me when the temps inside the coach get warmer, resulting in a net reduction in power consumption.
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Old 12-25-2020, 07:34 PM   #13
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My fridge is a Vitrifrigo with just shy of 6 cu ft. Don't remember the model number. It uses basically the same Danfoss compressor as many other DC compressor units.

It's not as big as the residential mentioned above, but the guts in mine are also used for larger units that they sell. The only real difference would be a longer run time to initially bring it down to temp, as the compressor would still pull the same current while operating. A bigger box doesn't change the draw on the compressor just the run time.

These things are so well insulated though that it constantly impresses me with how quickly it cools down.

One mod I made to it was to add a second fan on the compressor unit which runs constantly when the unit is turned on. At less than 0.25 amps, I find it worth it since it helps reduce run time for me when the temps inside the coach get warmer, resulting in a net reduction in power consumption.
Thanks.
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Old 12-26-2020, 05:54 AM   #14
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If you're comparing a residential fridge to an LP fridge being run on electrical power it's not a fair comparison. An LP fridge is designed to be most efficient running on LP, not electricity, and they will be power hogs on the cord. ,,,
The comparison was the fridge the OP listed as a replacement for his LP model. The very limited power consumption data available for the Dometic DMC4101 indicated that it might not be a good choice for an owner with a heavy off grid camping preference.

Owners need to run the numbers first. Do an energy, cost and size audit, before pulling the trigger to determine if what they want fits not only into the available space but also their preferred camping style.
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