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Old 05-02-2019, 11:56 AM   #1
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12 Volt Refrigerators

I must be missing something, but I can't figure out why we don't see 12 volt compressor fridges in RVs (at least I don't.) A nice, 9 cubic foot refrigerator/freezer that runs directly on 12 volts consumes around 520 to 580 watt-hours per 24 hours. I've calculated (conservatively) that a similar-sized 110 volt residential unit consumes about 1600-1700 w-h/24 hours, including the inefficient, but necessary, inverter. In other words, the 12 volt unit can run 3 times as long on the same battery power. Of course, the larger residential units found in many of today's RVs consume even more.

For RVers who are normally plugged in, it matters not, but for those of us who typically boondock, it can mean the difference between living delightfully on solar, or using a noisy, polluting generator daily.

The 12 volt fridges I'm thinking of are made for off-grid living and have high-efficiency, purposely-designed 12 volt compressors, and extra-efficient insulation. I suspect they're at least as rugged as the residential units RV manufacturers are installing today.

I'm looking at a residential fridge in a motorhome right now and wondering if I and a few robust friends can wrestle it out of that narrow little door. The orthopedic surgeon is on speed-dial.
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Old 05-02-2019, 12:20 PM   #2
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They're definitely out there, both as refit kits for propane or unit installs. Why they're not offered as original equipment is a good question. Good bet it's probably manufacturing economics or marketing. I have zero interest in having a 120V refrigerator and having to install and maintain the power system to run it, but I would definitely entertain a 12V compressor unit if/when my propane unit gives up. Alternatively, I'd also be happy to continue with a propane sourced fridge that used helium instead of hydrogen. Those exist too but I'm not aware of anyone offering those as original equipment either.

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Old 05-02-2019, 12:48 PM   #3
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It all boils down to $$$. The ammonia and hydrogen absorption fridges probably cost much less than a 12v compressor style fridge.

And before you ask about the fire issue, unless they are forced to by regulation install a different tech for fridges, they aren't concerned about your safety or the value you get from a thing. It's about the $$$.

My propane/electric fridge works great. I've taken good care of it. I've tried to have it as level as possible at all times when stopped. It uses very little electricity or propane. I inspect it every time I've moved from one place to another. Four years old and no troubles to report.
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Old 05-02-2019, 01:49 PM   #4
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Might be because they need bigger batteries and more solar than most folks have. It's cheaper to use the propane fridge with the 12 v heater. I would love a propane/compressor setup because I really have the wretched cooling power of our Dometic in hot weather. I do have the batteries and solar though.
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Old 05-02-2019, 06:14 PM   #5
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Originally Posted by Unpaved Road View Post
I must be missing something, but I can't figure out why we don't see 12 volt compressor fridges in RVs (at least I don't.) A nice, 9 cubic foot refrigerator/freezer that runs directly on 12 volts consumes around 520 to 580 watt-hours per 24 hours. I've calculated (conservatively) that a similar-sized 110 volt residential unit consumes about 1600-1700 w-h/24 hours, including the inefficient, but necessary, inverter. In other words, the 12 volt unit can run 3 times as long on the same battery power. Of course, the larger residential units found in many of today's RVs consume even more.

For RVers who are normally plugged in, it matters not, but for those of us who typically boondock, it can mean the difference between living delightfully on solar, or using a noisy, polluting generator daily.

The 12 volt fridges I'm thinking of are made for off-grid living and have high-efficiency, purposely-designed 12 volt compressors, and extra-efficient insulation. I suspect they're at least as rugged as the residential units RV manufacturers are installing today.

I'm looking at a residential fridge in a motorhome right now and wondering if I and a few robust friends can wrestle it out of that narrow little door. The orthopedic surgeon is on speed-dial.
My Navion came with a Norcold DC0061 12VDC only compressor fridge in it. You'll get a lot of anti-Norcold responses, now that I've opened that can of worms, but ours works fine. I think it pulls somewhere around 3Ah when the compressor is actually running. I've never thought to measure it, but I guess I should. The problem with the Navion's 12VDC fridge isn't the fridge, it's the inadequate little Group 24 FLA dual purpose batteries they installed at the factory to be the coach batteries. I plan to upgrade them some time this summer.
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Old 05-02-2019, 08:13 PM   #6
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Forest River is installing 22 cu ft LG three door residential fridges. We have a new 2019 Sandpiper with one. Included is a 2kw surge inverter attached to two size 27 deep cycle Interstates. System works well. We don't boondock but this system is supposed to work as the fridge is energy efficient Powered by it's own DC inverter from 120VAC for variable speed digital operation thereby using less power. We like it better than the previous ammonia models. We'll see.
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Old 05-02-2019, 10:02 PM   #7
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It all boils down to $$$. The ammonia and hydrogen absorption fridges probably cost much less than a 12v compressor style fridge.

And before you ask about the fire issue, unless they are forced to by regulation install a different tech for fridges, they aren't concerned about your safety or the value you get from a thing. It's about the $$$.

Iím not too sure about that statement. JC Refrigeration offers either 110v or 12v compressor cooling units to replace the OE ammonia absorption unit for a hundred dollars or so less than a replacement absorption unit.
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Old 05-02-2019, 11:25 PM   #8
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Iím not too sure about that statement. JC Refrigeration offers either 110v or 12v compressor cooling units to replace the OE ammonia absorption unit for a hundred dollars or so less than a replacement absorption unit.
jt
You said replacement. I'm talking about original equipment. Can JC Refrigeration supply the RV industry with enough refrigerators to keep the assembly line moving and profitable?

Yeah, anyone can replace a fridge with just about anything they want, but the RV industry is looking for profits, and my guess is the ammonia-hydrogen absorption fridges get them that or they wouldn't be using them.
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Old 05-02-2019, 11:55 PM   #9
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There are plenty of 12 volt fridges out there, the whole boating industry uses them and has for many years.

Propane fridges are not allowed in boats.

Big market for them in boats, but i don'tont know why the RV industry doesn't use them, except regular 120 volt models are cheaper.
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Old 05-03-2019, 08:06 AM   #10
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I just completed a modification of my 4 door Norcold to operate on 12 volts.
JC refrigeration make a kit to change out the entire cooling unit.

It took me a day and a half working by myself to do it. It works very well.
The power draw is 5.6 amps. Cost about $1200.

I considered a residential unit but did not want to run the inverter all the time as when it is on there is another 7 amps draw for other things like TV, DTV audio system and microwave even though they are off. I suppose if you plug in all the time this is not an issue but we do boondock.

Also to bring in a huge unit thru the door is a job as well as modify the cabinet space and customizing brackets to hold it in place. Wife was happy with the existing space.

I must add, I found a burned spot on the wall, we were close to having a fire in the rig, another reason to change this out.
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Old 05-03-2019, 08:57 AM   #11
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I hear ya. The first things I did when we took delivery of our new 2016 View was install solar and replace the 12 volt batteries with two 6 volt "golf cart" batteries. We can boondock indefinitely now.

I had no idea Winnebago now has the option of a 12 volt fridge.
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Old 05-03-2019, 09:05 AM   #12
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I hear ya. The first things I did when we took delivery of our new 2016 View was install solar and replace the 12 volt batteries with two 6 volt "golf cart" batteries. We can boondock indefinitely now.

I had no idea Winnebago now has the option of a 12 volt fridge.

Wasn't an option for me. That's what they put in it from the get go.

2018 model came with 2x100W solar panels up top (prior years only had 1x100W), and 2 marginal batteries down low.
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Old 05-03-2019, 10:29 AM   #13
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I must be missing something, but I can't figure out why we don't see 12 volt compressor fridges in RVs (at least I don't.) A nice, 9 cubic foot refrigerator/freezer that runs directly on 12 volts consumes around 520 to 580 watt-hours per 24 hours. I've calculated (conservatively) that a similar-sized 110 volt residential unit consumes about 1600-1700 w-h/24 hours, including the inefficient, but necessary, inverter. In other words, the 12 volt unit can run 3 times as long on the same battery power.
I am not sure about your match for efficiency, but DC compress* or is more efficient than AC for total energy consumption.

I think it is a combination of a few thing, but the trend is starting ! I know my next RV will have NOT have an "absorption" refrigerator. An ice maker would be WONDERFUL !
  • You need more battery power. Probably a minimum of TWO 6V golf cart batteries. Space and $$
  • For boondocking you need a solar power and/or a generator. More space and $$$.
  • Large RV want large refrigerators (< 9 cu. ft.) so residential is more logical. Also large RV probably do less boondocking and are more likely to have more battery capacity, solar/generator already.


Segue - WARNING for Techno Geeks only ! One of the most popular DC refrigeration compressors is made by Danfoss. Actually, Danfoss sold their refrigeration a few years back to Secop, but I think they are still using the brand name.

Most (all?) DC powered refrigeration compressors, convert DC to 3 phase AC and run a 3 phase AC motor to drive the compressor. Without going into details, this is much more efficient than a DC or even a single phase AC motor.
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Old 05-04-2019, 01:52 AM   #14
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I converted a chest freezer to a fridge, the thick insulation is a huge help and it isn't all that tough to do. Mine was 5cuft but I also have a smaller upright one. Anyway, it was using under 300 watts in 24 hours, roughly 12 watts per hour and rarely cycled. There are no 12v energy star units so I found it better to address my needs myself.
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