Refrigerator for off-grid cabin

[Horsefly]

Our off-grid cabin has had solar since 2017. Next spring I'm upgrading from 310Ah @ 24V AGM to 230Ah @ 24V LFP. Our original energy budget has proven to be very conservative, as I believe we almost never consume more than about 100Ah. The exception is hunting season, when a crowd of guys who are definitely not conserving energy crowd into the place for 4 days or so, and I don't think any size battery would be big enough for them. Good thing we have a generator.

We've had a propane refrigerator in the cabin since it was built in the 1970's. The current version (probably about 20 years old) has it's door seals failing, and we are getting tired of its inefficiency.

It appears that with the new battery we may be able to transition to an electric fridge. I'd probably prefer a 24VDC model, but if we need to leave the inverter on all the time I would just have to add in the tare losses in the inverter.

I've done some searches here looking for energy efficient refrigerators, but most seem to be in discussions about RVs or boats and so may be smaller or meant to meet requirements I don't have. We are hoping to find something over 10 cu ft (15 cu ft would be ideal), but I don't know exactly where to look. I know inverter refrigerators are much more efficient, but as far as I can tell they are mostly sold in Europe and Asia, but not here in the U.S. for some reason.

Anyone have some recommendations?

 

[sunshine_eggo]

I can't help you on specific models, but there should be plenty of energy star 120VAC models. I looked at replacing the absorption fridge in the RV, so I don't consume 4-5kWh/day, but we're not there enough to justify replacing it, and I can almost always power the absorption on AC for 8+ hours a day purely on solar - enough to keep mold from growing.

In my research, ~10cu-ft burned between .9 and 1.1kWh/day. Cost about $700 when I could find them (pre-supply crunch).

Via Google, this 12/24V unit claims 587Wh/day:

Unique 13.0 cu/ft Solar Powered DC Fridge Danfoss/Secop Compressor 12v - Ben's Discount Supply

(Shipping rates are based on the address you enter. Residential and liftgate fees are added for residential addresses. Business delivery or terminal pickups are usually much cheaper. Call 800-771-7702 or Text 833-852-4255 for all options). The Unique 370L1 DC powered fridge/freezer is designed...

bensdiscountsupply.com

 

[Horsefly]

That's a pretty good one @sunshine_eggo. Thanks!

24Ah on a 24VDC system is great. We could do that without breaking a sweat. Although, I'm not too sure about their math, since further down the page they say it consumes 67W, but that may be a max. My inverter (Schneider CSW4024) has a tear loss of 26W, so if the 24Ah is right I'd much rather go with DC.

 

[Simi 60]

Might be cheaper and easier in the long run to forget about expensive energy efficient fridges and spend the extra dollars on more battery, better inverter and solar.

We run multiple large 240v fridge freezer on our boat, out full time, very rarely does the genset get used as she has a good solar array

 

[sunshine_eggo]

That's a pretty good one @sunshine_eggo. Thanks!

24Ah on a 24VDC system is great. We could do that without breaking a sweat. Although, I'm not too sure about their math, since further down the page they say it consumes 67W, but that may be a max. My inverter (Schneider CSW4024) has a tear loss of 26W, so if the 24Ah is right I'd much rather go with DC.

I expect 67W is the max running consumption.

24V seems to be a really sweet spot for efficient refrigeration. I've seen 12/24V electric coolers that have notably less consumption (per the specs at least) when running 24V vs. 12V

120VAC:

https://www.lowes.com/pd/Frigidaire-11-6-cu-ft-Freestanding-Mini-Fridge-Freezer-Compartment-Stainless-Look/1001229218

11.6cu-ft uses 310kWh/year or 0.85kWh/day.

I can set aside my disbelief of the 24VDC unit, BUT both are likely optimistic. Take the 0.85kWh/day and add another ~.5kWh/day for the inverter idle burn, and it comes down to a ~$1200 difference to burn 0.6kWh/day (11% of battery capacity) or 1.3kWh/day (22% of battery capacity).

Personally, I'd double the battery size and go for the 120VAC unit for the same ~$1200

 

[Horsefly]

Personally, I'd double the battery size and go for the 120VAC unit for the same ~$1200

Ugh. I just spent way too much time building a nice insulated battery box for my 8S 230Ah battery.

But, you (and @Simi 60) have a point. I am somewhat over-paneled, with 1700W of panels, which maxes out my 60A SCC. I probably could add some more battery, but.... My partners in the cabin won't blink at spending $2K for a fridge, but they would be loathe to adding more panels. Long story.

The Google helped me find that same fridge at Home Depot (same price), with free ship-to-store. We couldn't get it delivered to the cabin anyway (30 mi of dirt roads to get there), so picking it up is fine. I owe you one @sunshine_eggo!

 

[sunshine_eggo]

Ugh. I just spent way too much time building a nice insulated battery box for my 8S 230Ah battery.

Ummm... build a second one... cut holes for beefy interconnects to parallel them. Should be cheaper and faster since you've already done it.

But, you (and @Simi 60) have a point. I am somewhat over-paneled, with 1700W of panels, which maxes out my 60A SCC. I probably could add some more battery, but.... My partners in the cabin won't blink at spending $2K for a fridge, but they would be loathe to adding more panels. Long story.

No need for more panels even if you double the battery. LFP doesn't care if you charge it at 0.01C or 0.5C (lower is less stressful), but unlike lead-acid, which needs a range, LFP will just happily take as little as you want to provide.

The Google helped me find that same fridge at Home Depot (same price), with free ship-to-store. We couldn't get it delivered to the cabin anyway (30 mi of dirt roads to get there), so picking it up is fine. I owe you one @sunshine_eggo!

If I'm ever in the area, a beer or soda outta that fridge will be just fine.

Honestly, if you have a kill-a-watt meter, I'd be really interested in hearing how it actually performs. Rather than going through the hassle of replacing an RV fridge, I've been contemplating just getting one in the container and moving the RV fridge contents into it when we're not there. Even just 8-10 hours on the absorption fridge during solar gobbles >2X more than that fridge uses (by the numbers anyway).

 

[chrisski]

has it's door seals failing,

I take it the door seal can't be replaced?

When the propane is running on my 12 votl fridge, it still pulls a half amp (6 watts), but only burns about a candle's worth of propane, which is so small I can't actually measure it, so I have no intention of replacing until it dies. The same fridge on electric gets 300 watt hours.

24Ah on a 24VDC system is great. We could do that without breaking a sweat. Although, I'm not too sure about their math, since further down the page they say it consumes 67W, but that may be a max. My inverter (Schneider CSW4024) has a tear loss of 26W, so if the 24Ah is right I'd much rather go with DC.

24 ah @ 24 volts a day is awesome for an electric fridge. That would definitely be a contender once the propane fridge is no more.

 

[Isaac-1]

There are some very efficient DC powered RV refrigerators out there these days with certain models of Danfoss brand compressors See this example only 78 watts while running https://www.toolots.com/mr-frozen-home-refrigerator-bcd-198.html

 

[RVLiFe]

LG 20 cu. ft. refrigerator - LTCS20020W

Might be something to consider to keep the beer cold

 

[Horsefly]

No need for more panels even if you double the battery. LFP doesn't care if you charge it at 0.01C or 0.5C (lower is less stressful), but unlike lead-acid, which needs a range, LFP will just happily take as little as you want to provide.

Yeah, I may think about that. It may make sense even if we don't to an AC fridge.

I take it the door seal can't be replaced?

It's a 20+ year old absorption fridge, and my sister and her husband said an exact replacement can't be found. I'm just taking their word for it.

If I'm ever in the area, a beer or soda outta that fridge will be just fine.

You'll be ready for a beer after driving for an hour on that access road to our cabin.

 

[Bvillebob]

I bought a Truckfridge for my camper, a 12v Danfoss compressor model. It uses 2.4 amps at 12v, say 35 watts or so, and runs about 20 percent of the time, so very little power use and keeps stuff really cold. They make them in a range of sizes, worth checking out, I love mine, it's made long term camping (3 months a year) so much more pleasant.

 

[Notes]

Horsefly, try Refrigeration Hardware Supply. ( RHS.Com ). They can custom make any type fridge/freezer door gasket. I use them for all my gasket needs.

 

[Horsefly]

Horsefly, try Refrigeration Hardware Supply. ( RHS.Com ). They can custom make any type fridge/freezer door gasket. I use them for all my gasket needs.

Thanks for that @Notes! I'll take a look at it. Thing is, it seems that once everyone understood what the new batteries would do, they want to kick the 20+ year old propane fridge to the curb!

 

[BarkingSpider]

I am very impressed with this traditional looking, stainless steel 110v fridge/freezer unit from Amazon.

It uses very little power, the compressor runs for around 10 minutes per hour and consumes around 50w when running. The actual runtime depends on the ambient temperature. I'm in California.

It starts up using a 1500w inverter and has been running in my off grid cabin for 2 years.

Perfect for beer and icecream and under $200!

Amazon.com

 

[Horsefly]

I am very impressed with this 110v fridge/freezer unit from Amazon, it uses very little power when running, the compressor runs for around 10 minutes per hour and consumes around 50w. It starts up using a 1500w inverter and has been running in my off grid cabin for 2 years. Perfect for beer and icecream!

Amazon.com

Thanks @BarkingSpider. Our current fridge is 8cf and I'm told by the foodies that it is too small. So a 3.1cf won't do. It does look like a good one though.

By the way: Your forum name was the subject of lots of my dad jokes when my kids were growing up.

 

[BarkingSpider]

Consider buying 2, it's so low cost and efficient, it's a real option. Plus you can half your power requirements when you don't need 2.

 

[12VoltInstalls]

Just a thought. There was a 11/12-ish cubic foot 120V fridge at Home Depot last summer around $350, 80W. So for a couple more panels (and maybe not more batteries?) you could have the fridge at smaller dollars and more robust deer camp power both. I wish I’d bought that size but I got a 5CF for $149ish, delivered.
Sure the 24V units are “efficient” but a couple panels snd a cheaper fridge may be the dollar efficiency you’re looking for.

 

[PlanetExcellent]

We have a Norcold 12-volt 10 cubic foot model in our trailer and we love it. They have another one that is 15 cubic feet I think.

Polar N10DC | State-of-the-art DC Compressor RV Refrigerator | Norcold

Built-for-the-road DC compressor RV Refrigerator with freezer compartment. Polar N10DC comes with eye-level LED display, touch controls and adjustable thermostat that responds to ambient changes.

norcold.com

 

[Don B. Cilly]

My 220V cheap fridge draws some 70W. It starts up approximately every 45 minutes and runs for some 15.
It starts off at about 80-90W, then quickly settles to some 50-60.

I'm thinking of getting a 24V Danfoss compressor for it - not so much for power (some gain might be expected) - but for noise.
The noise is not loud, but in total silence, it's annoying. It's a "bzzzz" thing, and I quite dislike it.

Now, I'm not sure a DC compressor would be quieter - though I guess it should be.
Does anyone actually know? I had a 24V fridge compressor on a boat for years, and it made no noise, but it sat in a heavily insulated engine room. I never noticed any noise in the engine room itself either, but I can't be sure. It was the type with a separate motor and a pulley.
.