12 volt refrigerator, yes or no

[Marine359]

I don’t have a better measurement tool than my smart shunt. It may not be as accurate as os laboratory instruments, but my guess is that it is the most accurate tool one can buy for an rv. Of course to obtain accuracy, you must first charge your battery to 100% SOC (when it no longer accepts a charge), then reset the shunt so it also reads 100%.

I know that my 10cuft Dometic compressor fridge consumes nominally 50 amphrs per day. That’s equivalent to 2,050 btus using the amphr to btu conversion chart @ 12v. But that’s not completely fair because this figure alone presumes your battery amphr capacity is unlimited. Instead, I also calculated my propane generator requires onsumes 0.15 gallons of propane per hour. And I have observed that in 50 minutes it replaces the 50 amp hours used the prior day by the fridge. Or approximately 12,800 btus. O you can logically choose a baseline daily btu consumption between 2,050 btu and 12800 btus per day. Of course if the sun is good, I replace can the amphrs with solar, which eliminates the generator useage, and contributes to pushing the battery capacity along a curve towards unlimited capacity. That means with unlimited good days of sun, you’re only going to use 2,050 btus.

On the absorption side, I just used mfg spec for a Dometic 8 cuft fridge. It’s rating is 1,500 BTU/hour. That would be 36,000 btus per day. And that doesn’t include the BTU’s needed from the on the 12v side. Now, of course I can’t obtain accurate measurements of propane consumption because I no longer have an absorption fridge. I’m “guessing” that the fridge does not consume a full 1,500 btu/hr once it’s cold, but I don’t know for sure.

You can probably provide a more accurate picture of propane consumption, and therefor btu consumption for the absorption fridge noted.

Unless my math and logic are way out in the woods, the compressor fridge is substantially more efficient in terms of btu consumption. I’ll stick with 50%, although that’s not scientific. More of a SWAG. I think you know what a SWAG is.

Curious to hear what your real world observations are for absorption fridge energy consumption. The media apparently believes that compressor fridges are more efficient than I’ve claimed. And of course efficiency means very little if your equipment meet or exceed your real world needs.

As I mentioned, I have no data on longevity, only parenthetical observations of my experience with residential fridges. BTW, I’ve never had an absorptio fridge fail on me, or need to be repaired.

[runamuck]

dometic/everchill/furion/norcold all have 12v fridges in the 1600$ range ( up a cpl. hundred from just a month ago). not that hard to R&R oneself. I doubt I would ever want to pay the shoddy service department of any of the local dealers 2500$ to do the work. how would this be against the law anywhere to DIY this kind of thing. not trying to stir things up but this is a project I have been considering if we dont trade trailers any time soon. just about all the new ones have 12v now as from I can tell, they are cheaper to buy and a larger one will fit in the same space as a smaller 2 fuel one.

[Marine359]

Good deal Runamuk,
Just saying that in my state, for residential installation of gas lines and appliances, you have to use a licensed contractor. I don’t know if that is the case with rvs and absorption fridges. If you can DIY an absorption, then I wish you good luck with the project. Although I consider myself a capable DIYer, I would be afraid to attempt that project with my skill base. Let us know how the project goes. I have successfully re-installed my 12v fridge, and it wasn’t a big deal. Installing a 12v where there was an absorption shouldn’t be much harder. You’d just need to make sure you get the wiring right. May require larger gauge wire than the ones hooked up to the absorption fridge. I see the Dometic 10cuft DMC4101 advertised for $1,500. Will fit same space as Dometic 8cuft absorption.

[dsrace]

Originally Posted by Skibane

If you've abandoned your 30 lb propane tanks, what are you using to heat your RV with
?

What are you using to cook with?

Heat your water with?

Run your propane generator with?

???? https://youtu.be/v5hl5z875Vk

[dsrace]

i optioned in a dometic DMC4101 10 cu ft into our new dune sport toyhauler. i can say as of now, i wouldn't go any other way! this is the 4th toyhauler we have owned in the last 20 years. kept the fifthwheel 295 wolf pack for 10 of those years. all of the previous had an absorbtion ( what i called standard rv fridge) in them. no matter what aftermarket product i tried they never worked as well as i would've liked. so our first trip out with the dometic.......

85* day, 4 hrs and it was food safe on start up
3 power level settings and started in on high ( performance)
set power level on eco for travel ( 3.5 amp draw when cycled)
dropped temp setting in fridge from 4 to 3 and left freezer
once we arrived ( 7hr drive) connected to shore power i turned it back up to level 4 ( performance)

next morning cans of soda in the fridge were bulged getting ready to pop
turned temp down to #2 temp setting in fridge and freezer to 3/4


i have never, in all the campers i have owned, had to turn the temp down in a fridge! i was lucky if the freezer would slush soda in 6 hrs!

with the dometic, there are 3 power levels. i have not tried level 2 and adjusted temps to see how well that works yet. i was sold after the first trip and at this point, cannot imagine going back. we only have 200 watts of solar that i am just finishing up. i know that is not much at all, the goal was to support the fridge while keeping the battery charged. clearly performance mode draws more then the panels produce, there are a couple trips we like to take that require a short overnight nap after a 9 or 10 hr drive. atleast the 200 watts will start to contribute shortly after day break. we have a single renogy agm 200 ah battery.


here are a couple links that nudged myself in this direction.....


https://www.rvtravel.com/rv-electric...ic-12-volt-dc/


https://www.rvtravel.com/rv-electric...-usage-part-1/

[Dave Pelletier]

I remain mystified about all the stories of poorly performing absorption fridges. I put a bottle of room temperature water in my freezer yesterday and it was frozen solid within a few hours. .....on level 3 of 5. I don't know what the fridge temp is but the room temp water bottles I put in it are very cold (just how I like them). I've had 5 absorption fridges over the years and haven't had a problem with the performance of any of them - they seem to do as good as the 6 compressor fridges in my house.....just an observation.

Dave

[Marine359]

Dsrace,
You should be in great shape with 200w solar and 200ah AGM. The fridge uses 50ah/day nominally. So you’ve got plenty of battery, assuming you don’t mind discharging to 70% DOD. If sun is favorable, you’ll be able to boondock for a long time without generator, and not have to deeper than 50% DOD. Our little 120w portable panel farms about what the fridge uses on a good day. Yours will more than offset fridge consumption. BTW, we’ve toyed around with the DMC4101 settings, and found performance level 1 works best for us.

[xrated]

Originally Posted by Dave Pelletier

I remain mystified about all the stories of poorly performing absorption fridges. I put a bottle of room temperature water in my freezer yesterday and it was frozen solid within a few hours. .....on level 3 of 5. I don't know what the fridge temp is but the room temp water bottles I put in it are very cold (just how I like them). I've had 5 absorption fridges over the years and haven't had a problem with the performance of any of them - they seem to do as good as the 6 compressor fridges in my house.....just an observation.

Dave

Have you ever owned a Norcold 18 cu ft 4 door model as one of your absorption fridges? If you have, you likely have about a 50/50 chance of working correctly. Lots and lots of the larger camping trailer and Toy Hauler like I have, has that one in it. It has been a POS almost since the day I bought the trailer. My wife and I and our furry pet are headed to Indiana next month to have JC Refrigeration do it magic and mod our $4000+ "Nevercold" into a 12VDC twin compressor fridge. I've had it with the....maybe it will work this time....maybe it won't crap. I'm over it, as an absorption fridge.

[Dave Pelletier]

Originally Posted by Marine359

Dsrace,
You should be in great shape with 200w solar and 200ah AGM. The fridge uses 50ah/day nominally. So you’ve got plenty of battery, assuming you don’t mind discharging to 70% DOD. If sun is favorable, you’ll be able to boondock for a long time without generator, and not have to deeper than 50% DOD. Our little 120w portable panel farms about what the fridge uses on a good day. Yours will more than offset fridge consumption. BTW, we’ve toyed around with the DMC4101 settings, and found performance level 1 works best for us.

I have 320watts of solar and 450 AH of lead acid so about the same as 200ah of lithium. My concern is that in poor solar conditions, I could run my battery bank down to 50% in 4-5 days....with just the 12v compressor fridge. Considering the furnace is the bigger draw, plus all the other little things, my boondocking time (weather dependant, of course) could be limited to a couple days before needing to run a generator which I reeeealy don't want to do. Yes, you could just keep adding batteries and solar until you have the longevity you desire but it's not a cheap solution by any stretch. I fully understand the advantages of a 12v compressor fridge, particularly in a brand new unit but propane consumption, any increased fire hazard and poor performance aren't big concerns for me based on current and past experience.

BTW, I just wanted to thank you for your informative and thought provoking posts. Cheers,

Dave

[Dave Pelletier]

Originally Posted by xrated

Have you ever owned a Norcold 18 cu ft 4 door model as one of your absorption fridges? If you have, you likely have about a 50/50 chance of working correctly. Lots and lots of the larger camping trailer and Toy Hauler like I have, has that one in it. It has been a POS almost since the day I bought the trailer. My wife and I and our furry pet are headed to Indiana next month to have JC Refrigeration do it magic and mod our $4000+ "Nevercold" into a 12VDC twin compressor fridge. I've had it with the....maybe it will work this time....maybe it won't crap. I'm over it, as an absorption fridge.

Nope; currently have an N8X and had an N7 in my last trailer......others have been primarily Dometic. I don't blame you for wanting to switch if you've had problems and clearly some do......I just haven't had any and neither have any of the friends we regularly camp with.....maybe we're all just lucky.


Dave

[dsrace]

Originally Posted by Dave Pelletier

I remain mystified about all the stories of poorly performing absorption fridges. I put a bottle of room temperature water in my freezer yesterday and it was frozen solid within a few hours. .....on level 3 of 5. I don't know what the fridge temp is but the room temp water bottles I put in it are very cold (just how I like them). I've had 5 absorption fridges over the years and haven't had a problem with the performance of any of them - they seem to do as good as the 6 compressor fridges in my house.....just an observation.

Dave

just as you are mystified about all the stories of poorly performing absorption fridges i too am mystified that you've have had 5 good ones. imo and only imo that is fantastic luck on your part. i do not doubt it for a second either and am not saying this in a derogatory manner. out of the 4 i used ( do not remember the brands but all 8 cu ft) none of them performed as i expected. now having said that, i must state, that i expected something between what i received and a household fridge. i knew they would never perform as well but in the ball park atleast. yes, i could place a bottle of liquid in the fridge and with in a 5 to 6 hrs they were cold enough to drink but not cold like a household fridge. the freezers would keep food frozen for the ( longest camping trip was 1 week) duration of our stays. now by the end of a week, i wouldn't put those items back in the freezer at home. lets put it this way, on one trip, for some unknown reason, someone put the eggs in the freezer. kids do strange things i guess. the next morning i found them, pulled them out and they were just on the verge of frozen. all frozen food in the freezer but did freeze eggs overnight. now that was one instance and by no means an across the board comparison. i could put soda in the freezer and with in 2 hrs it was slushy. slushy coke mixes very well with JD on a hot day. none of the fridges had actual temp settings/dials. they all had a probe that slid up and down on the aluminum cooling fins. i tried fans in the vents outside, tried the solar roof top vent with fan, even tried the twin cooling fans inside the fridge that wired into the light. yes they all did help but only a tiny amount. btw, one of the units had a factory fan mounted to the coils. after adding the fan up at the roof top vent it was def louder. not horrible by any means just noticeable. i do not know of a friend or family member that has ever been happy with their absorption fridge. i do acknowledge the benefits of that style and w/o solar or even with min solar they are more user friendly on a power stand point. i am glad you have had nothing but good fridge's i wish everyone would, but for ourselves, this dometic is spot on.

[Dave Pelletier]

Originally Posted by dsrace

just as you are mystified about all the stories of poorly performing absorption fridges i too am mystified that you've have had 5 good ones. imo and only imo that is fantastic luck on your part. i do not doubt it for a second either and am not saying this in a derogatory manner. out of the 4 i used ( do not remember the brands but all 8 cu ft) none of them performed as i expected. now having said that, i must state, that i expected something between what i received and a household fridge. i knew they would never perform as well but in the ball park atleast. yes, i could place a bottle of liquid in the fridge and with in a 5 to 6 hrs they were cold enough to drink but not cold like a household fridge. the freezers would keep food frozen for the ( longest camping trip was 1 week) duration of our stays. now by the end of a week, i wouldn't put those items back in the freezer at home. lets put it this way, on one trip, for some unknown reason, someone put the eggs in the freezer. kids do strange things i guess. the next morning i found them, pulled them out and they were just on the verge of frozen. all frozen food in the freezer but did freeze eggs overnight. now that was one instance and by no means an across the board comparison. i could put soda in the freezer and with in 2 hrs it was slushy. slushy coke mixes very well with JD on a hot day. none of the fridges had actual temp settings/dials. they all had a probe that slid up and down on the aluminum cooling fins. i tried fans in the vents outside, tried the solar roof top vent with fan, even tried the twin cooling fans inside the fridge that wired into the light. yes they all did help but only a tiny amount. btw, one of the units had a factory fan mounted to the coils. after adding the fan up at the roof top vent it was def louder. not horrible by any means just noticeable. i do not know of a friend or family member that has ever been happy with their absorption fridge. i do acknowledge the benefits of that style and w/o solar or even with min solar they are more user friendly on a power stand point. i am glad you have had nothing but good fridge's i wish everyone would, but for ourselves, this dometic is spot on.

Yes maybe the 5 I've had and the 20 or 30 my friends had are all flukes? I keep food (catsup, mustard, butter, etc.) in my fridge and frozen stuff in my freezer (hotdogs, hamburgers, etc.) for 6-7 months of the year. Anything in my freezer is frozen rock hard just like my home freezer. I take anything left over at the end of the season and put it back in the house freezer.



Dave

[dsrace]

Originally Posted by Dave Pelletier

I have 320watts of solar and 450 AH of lead acid so about the same as 200ah of lithium. My concern is that in poor solar conditions, I could run my battery bank down to 50% in 4-5 days....with just the 12v compressor fridge. Considering the furnace is the bigger draw, plus all the other little things, my boondocking time (weather dependant, of course) could be limited to a couple days before needing to run a generator which I reeeealy don't want to do. Yes, you could just keep adding batteries and solar until you have the longevity you desire but it's not a cheap solution by any stretch. I fully understand the advantages of a 12v compressor fridge, particularly in a brand new unit but propane consumption, any increased fire hazard and poor performance aren't big concerns for me based on current and past experience.

BTW, I just wanted to thank you for your informative and thought provoking posts. Cheers,

Dave

couple of questions, your 320 watts of solar, is that a suit case set up or or roof mounted? just curious and i am not that familiar with diff solar set ups and do not pretend to be, that is why am asking.



my battery is only a 200 ah agm by renogy. lithium would be better and the prices have come down a bit however i am not changing until this one is shot. i can only use 100 ah out of it still and i wired my panels in parallel as i am using the renogy adventurer pwm controller. i was concerned about shading. long story on the pwm but wasn't my choice as i didnt know that's what they installed so i am happy they wired in the batt temp sensor and i added the bt function. i can swap it out to an mppt but don't need to at this point. based on the links i posted, in theory i could run 22 hrs w/o any solar with an actual available 100 ah.



obviously that is only one day and fridge only. which is why i can easily see your point of view as well.

[dsrace]

Originally Posted by Dave Pelletier

Yes maybe the 5 I've had and the 20 or 30 my friends had are all flukes? I keep food (catsup, mustard, butter, etc.) in my fridge and frozen stuff in my freezer (hotdogs, hamburgers, etc.) for 6-7 months of the year. Anything in my freezer is frozen rock hard just like my home freezer. I take anything left over at the end of the season and put it back in the house freezer.



Dave

exactly my point, yours have all been far more efficient then the ones i have had! food was never frozen rock solid still at the end of a week. it wasn't thawed either but you could tell it was on its way. fluke or not, i am glad you all have efficient fridges, seriously. i have yet to experience an absorption rv fridge that does as you describe, that doesn't mean they don't exist, just means they have not existed in any of my campers.



lets put it this way....... if the last 4 trucks you have owned never worked right and nothing seemed to fix them, would you continue to buy that brand/engine? might be 1 million others that state they have had great luck with there's. they also may have diff expectations from their pick ups.