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WOW! Absorption fridge vs compressor fridge

I installed a Unique 12 volt compressor fridge about a year ago. I love it. It works very well and I run it for the entire camping season off of my solar system. My Norcold was very inconsistent and affected by the sun shinning on the side of the trailer. It would get warm in the day and too cold at night unless I adjusted the settings after sunset.

I went we the Unique because Home Depot sells them online and will ship them to your local store for free pickup. These fridges are made by a Canadian firm that markets to off grid cabins.

Got a link? The one I could find on the HD site was $1800.
 
Absorption fridge - 514ah (6737wh)
compressor fridge - 74ah (984wh)

2.2lbs of Propane

1 kg = 13.6 kWh of energy from LPG which burns at almost 100% efficiency :p


So my my 40 lbs propane tank on my RV is about 18kg of Propane, with a margin of safety about 15kg

15kg * 13.6 kWH = 204 kwh of stored energy
204kwh / 6.7 kWh per day = roughly 30 days.

Yes it's inefficient, but man, you got a 30 day battery with propane. If you are not a full timer, it's still very economical.

I had a compressor fridge and now I like the silence of my propane absorption one. I use the RV about 60 days a year - that means - twice a year I have to buy propane. Putting in a compressor fridge conversion, doesn't make any sense until LFP is $100 per kwh.
 
Yes but that’s typical of most 12v against 240v fridges with the 240v being so much cheaper. Absorption fridges are a ripoff no different. Have a look at the price of a car fridge. No different. You dont say to people run a Kogan 240v fridge off an inverter instead of a 12v car fridge!
because a LPG fridge is cheap, silent and perfectly adequate for people which are not using the RV very often. When you are not boondocking and the campground supplies the power? Further even when you are boondocking - the propane fridge runs for a month or longer on the LPG tank. Without dependency on Sunshine.

When I go camping I like to park in the shade, there the absorption fridge works amazing - but I don't get enough solar to power a DC fridge.
I'm a light sleeper, and compressor of my old fridge regular woke me up. Especially in a small RV.

Absorption fridges have their use case - it's just not the electric one.

I'm currently working on an idea of supply the absorption fridge directly with from the solar system or engine - (water or coolant)
You get heat everywhere as a waste product - just need a way of using it in the fridge.
 
I bought the 6 cubic foot version because that was what would fit in the space I had. My Norcold was also 6 cubic foot. I paid $949 February 2020 which was $50 off the normal Home Depot price. They have gone up since since the same fridge at Home Depot is now $1299. Last year Costco was selling the 10.3 cubic foot DC version online for $999. COVID must have affected the cost of the Danfoss/Secop compressors. $949 was a good price compared to the other options I saw that required shipping. I wanted 12 volt version so I didn't need to run my Multiplus 3000VA inverter/charger all the time.

I would have loved to install the 10 cubic foot version but my fridge is above my furnace air return and I just didn't have the free height available. The 6 cubic foot version is fine for us. I have an Engel chest freezer that can go in the back on my truck under the Leer cap and run off the solar on the truck cap if we need more capacity.

I was able to add 2 inch foam board on the right and left side of the fridge and 1 inch foam board against the wall in back of the fridge. I added 1 inch to the top of the fridge. I had a 4 inch clearance behind and above the 1 inch foam board on top. I run three 40mm Noctua fans at the top which pull trailer ambient air up the back side of the fride where the exposed coils are located. The fans and compressor are very quiet. I can't hear them more than a couple of feet away from the fridge. The top vent was sealed with 2 inch foam and the wall outside vent was made water tight and permanently sealed up since the inside foam board blocked access anyway. My trailer is quieter now without the open vents behind the old fridge system.

I have a 3 inch wide board that slide into a slot on each side of the front of the fridge securing the fridge and freezer door during travel.

DC-FridgeInstall.jpg
 
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Here is a photo showing the added insulation on the sides and back. It also shows the vent providing air flow the is being pulled up the coils from the Noctua fans installed above the fridge.

FridgeInsulation.png
 
Here is a photo showing the added insulation on the sides and back. It also shows the vent providing air flow the is being pulled up the coils from the Noctua fans installed above the fridge.
do you got a picture from the back of the fridge? I haven't see a fridge with coils in a long time.
 
Sorry, I don't have one. The manufacture doesn't have one on their site either. Most coils now are under the fridge where they are excellent filters for pet hair.

My coils are black and cover the upper 3/4 of the back of the fridge above the access to the compressor near the bottom.
 
My coils are black and cover the upper 3/4 of the back of the fridge above the access to the compressor near the bottom.
this is like fridges looked for 50+ years until they began shuffing the coils underneath in the 2000s.

Those new style fridges need a ton more energy, and are more prone to fail (they usually die when the fan dies)
You put hot coils, where air rises underneath the object your are trying to cool. Stupid design all around

- glad that this fridge goes back to the thermodynamic correct way of getting rid of heat
 
I found this schematic diagram showing the back side of the fridge. It is a good representation of what the coils look like. I think the larger surface area and vertical orientation helps dissipate heat beater than coils under a fridge. I corrected my previous post. I have three 140mm not 40mm Noctua fans to blow air out over the top of the fridge and pull ambient air up over the coils in back.

UniqueFridgeBack.jpg
 
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Coils on the back may work out better when replacing an absorption refrigerator. Especially if the sides of the enclosure are tight up against the refrigerator. I'll have to check to see how much room exists in the compartment where the current absorption refrigerator sits.
 
Putting in a compressor fridge conversion, doesn't make any sense until LFP is $100 per kwhr

Not quite, at least in my case. My primary reason for changing the fridge was dramatically increased (almost 50%) space inside the fridge for the same footprint. The compressor fridge doesn't have all the radiating fins, tubing, burners, etc. that the absorption fridge had and so there is more freezer and fridge space as a result. My second motivation was not having to travel with a propane burner actively running to maintain the temps in the fridge/freezer. For short trips it didn't matter. It would hold temps fine without any refrigeration. But for longer trips, I would turn on the propane burner but hated traveling that way. To each their own.

The added benefit is I can just now let my fridge run 24/7 during camping season (about April-November for me) and not have to completely load and unload for each trip.

I sized my solar, batteries, and inverter for running air conditioning while off-grid. And, since my compressor fridge is built in to the cabinet, I don't hear any compressor noise.

You've posted your propane cost data before. For some of us, the economics of using propane wasn't even a consideration.
 
I'm in the same boat, it made sense to me for several reasons, the increase of space in the fridge (going from 18cu/ft to 21cu/ft), and the fridge was atleast 6 inches deeper, but I also got more features, a better layout of shelves etc, an ice maker and water/ice dispenser in the door, it auto defrosts (big deal to me as I hate having to defrost my old fridge every couple months), and my ice cream is actually rock hard at -5* instead of the garbage 22* freezer. My fridge also was hit directly with the sun for 4-5 hours a day, and it plowed through propane. I was getting 14gal of propane (2x 7gal tanks) every 2 weeks.

10/10 would do it again. Never going back to an absorption fridge.
 
The added benefit is I can just now let my fridge run 24/7 during camping season (about April-November for me) and not have to completely load and unload for each trip.

I sized my solar, batteries, and inverter for running air conditioning while off-grid. And, since my compressor fridge is built in to the cabinet, I don't hear any compressor noise.
Everyone has a different use case your camping season for instance is during periods of high sunshine.

I'm around Florida, my camping season is upside down - October - through May. Where it's not hot and I got short days.

I'm not against DC Fridges, hope that didn't got over the wrong way - I'm very likely going to get one for my house - where it runs 24/7 for all year round. There it makes perfectly sense.

For the RV - I'm waiting till the DC fridges are a similar price like an AC fridge. Currently they are a novelty - a 6 cubic fridge shouldn't be $900.
The manufacturer use the same exact piping, frame layout as for AC fridges - switch the $30 AC compressor for a $60 DC compressor and asking for $500 more.

Nice profit :p
 
I didn't go for the 12 volt compressor fridge until I had a very large solar and battery system. The system was sized for generator free air conditioning. At that point I knew that the compressor fridge was going to work for me regardless of the time of year. I do notice the reduction of propane use after converting the fridge. I also run my water heater on solar for much of the day when I am not using the air conditioner.
 
The manufacturer use the same exact piping, frame layout as for AC fridges - switch the $30 AC compressor for a $60 DC compressor and asking for $500 more.

Nice profit :p
Right? "Research and development costs" to have one less cable (2 for DC vs 3 for grounded AC).
Cold boxes have got some way to go before everyone has their ideal efficient solution that can run as much as wanted ?

I'm a big fan of adding insulation and supplementing the cooling with fans. Sadly not all models allow this sort of mod.
 
Why DC fridge? No gas.

No need for leak detection, no need for CO alarm (I have electric stove), no worry that my absorption fridge will burn down my camper.

And when you compare LPG to electricity, I'm not sure if the cost balance is that bad- and I know my battery has more than enough storage to drive all day without charge to run my fridge.

Extra bonus- the fridge we got has way more interior space vs. an equal exterior space three way.

Yea, AC compressor fridges are way cheaper than DC, but three way's are not nearly that much cheaper than DC. The real comparison should be AC with inverter vs. DC and/or three way- not gas vs compressor.
 
I did the JC Refrigeration conversion back in 2019. I got the 12 Volt DC model because I didn't want to get involved in putting an inverter in. I don't think the 12 VDC refrigerators were out at that time or I was just not aware of them. The conversion works reasonably well but as others have said you have the smaller space of the absorption fridge.

I think the limitation of the absorption fridge is that they just don't have the cooling capacity. My fridge will cool down to temperature in 2 hours and once there the temperature is always the same. I have only had one time, on a hot day and the sun on the slide, when the temperature increased to the low 40s otherwise it will always hold at 36 with the setting on 3.

I haven't seen any camper with a larger 12VDC refrigerator option. So far they seem to be limited to 8-12 CD.
 
And when you compare LPG to electricity, I'm not sure if the cost balance is that bad- and I know my battery has more than enough storage to drive all day without charge to run my fridge.
I my last RV (campervan) I had a AC fridge with Inverter. (3,3 cubic)

Do get that thing to work as long as I want - 3-5 days - parked in the shade - I needed roughly 3 kwh of storage. + a little bit of extra storage for the other conveniences. I had 200w of solar - but, since I camping during the winter in florida - in the shade - they are not doing that much.

That was $1000+ in batteries alone. The inverter runs at 95% so with a DC fridge it wouldn't be that much less.

With my 6 cubic absorption fridge in my new RV I'm going through maximum of $50 of propane year (including water heater, cooking and furnace)
That's a 20 year Return on Invest. (1000/50)
Many campgrounds have included hookups - where I don't care if the absorption fridge takes 6kwh a day.

Why DC fridge? No gas.

No need for leak detection, no need for CO alarm (I have electric stove), no worry that my absorption fridge will burn down my camper.
Former fire fighter here, most fires are electric :p sorry. Nr. 1 cause of RV (and residential) fires - is electrical, number two (with a large distance) is the Refrigerator.
And many times, the fridge burns because of electrical and not the propane side.
 
I think the limitation of the absorption fridge is that they just don't have the cooling capacity. My fridge will cool down to temperature in 2 hours and once there the temperature is always the same. I have only had one time, on a hot day and the sun on the slide, when the temperature increased to the low 40s otherwise it will always hold at 36 with the setting on 3.
many absorption fridges are terrible installed by the RV builder. Not a fault of the technology.
They need airflow in the back and in the compartments. My absorption fridge had issues getting below 40F on hot days - on setting 5 out of 5.

I added a $12 computer fan in the back - which runs 24/7 on 0.12A and now the fridge sits at 32F on setting 3 out 5. at 95F outside.

If you install DC fridge without taking care about the airflow - it will not work either.
 
many absorption fridges are terrible installed by the RV builder. Not a fault of the technology.
They need airflow in the back and in the compartments. My absorption fridge had issues getting below 40F on hot days - on setting 5 out of 5.

I added a $12 computer fan in the back - which runs 24/7 on 0.12A and now the fridge sits at 32F on setting 3 out 5. at 95F outside.

If you install DC fridge without taking care about the airflow - it will not work either.
Reminding myself to check the fridge vent on my camper...
 
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