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Small Cabin Forum / Off-Grid Living / Efficeint fridge?
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rachelsdad
Member
# Posted: 22 Jul 2022 03:40
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We have a 10 +/- cubic foot propane fridge at the cabin but I was hoping to switch out to an electric.

I have 4 x 1kw Volts and we really only use the LED lights sparingly on summer...I'm usually asleep by dark!

We would unplug when not there.

Any recommendations?

Nobadays
Member
# Posted: 22 Jul 2022 08:43
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Quoted from a post I made in Aug. 2021... still true...

"We have a 10.1cuft Magic Chef that is rated at 297kw/year, about .81kw/day. The big box store near our home in AZ has it for $328.00. Another forum memeber says his in actuality uses .50kw/day. That might help. Keep in mind that refrigerator only actually runs ~8 hours per day."

I haven't looked for a couple of years, there may be a more efficient fridge out there now. This has been a good appliance for us.

gcrank1
Member
# Posted: 22 Jul 2022 09:39
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Ime at home as well as trying to run a 4.5cf Haier fridge at the cabin, it takes a while to get them down to temp. That means if you start out shut off it is going to take max power for x hrs even if you put some cold stuff in there. Once the whole of fridge and food is cold it holds pretty good and cycles.
Fwiw, this summer our cabin interior has been into the 80s*F, an unpowered fridge would be too...inside and out. I venture to say it would take a good 1/2day for the fridge to get to safe 'fridge temp'?
So weve happily been using a mid-large size Yeti clone cooler with my own freezer water bottles from home; easy 3+ days of cold cooler so far for us.
My 2 elec fridge energy hog units are in the storage unit.

Notes
Member
# Posted: 22 Jul 2022 19:29
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I have a GE model GTE18GSNRSS 18cuft. I modified unit, I removed defrost heaters, frame and mullion heaters, replaced evaporator and condenser fan with ecm motors. Added a on/off switch to compressor for good old fashion manual defrost. The evaporator fan stays running in defrost for a quick defrost. We are located in upper peninsula Michigan. Stays on from March-December. Measured with kilowatt meter, average .48khw / day.

gcrank1
Member
# Posted: 22 Jul 2022 21:08
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Rdad, I cant remember what you have for bats and charging. I think that would be helpful for this discussion.

ICC
Member
# Posted: 22 Jul 2022 21:38
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What size of fridge is wanted?
Fridge with freezer?

Brettny
Member
# Posted: 23 Jul 2022 06:26
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I have one of these. It runs on solar just fine. I have 6 hc2 220ah batteries and only get about 3hrs of sun on pannels.
https://www.homedepot.com/p/Magic-Chef-4-5-cu-ft-2-Door-Mini-Fridge-in-Stainless-Look -with-Freezer-HMDR450SE/305026385?

paulz
Member
# Posted: 23 Jul 2022 08:42
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Quoting: Brettny
I have one of these. It runs on solar just fine. I have 6 hc2 220ah batteries and only get about 3hrs of sun on pannels.


What inverter are you using?

travellerw
Member
# Posted: 23 Jul 2022 23:02
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I will add some links when I'm back in town, but a freezer converted to fridge temps with a digital controller is the most efficient. A chest freezer is by far the best, but my missus said no way. So a stand-up freezer is close.

Brettny
Member
# Posted: 24 Jul 2022 06:47
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Quoting: paulz
What inverter are you using

Xantrax freedom x1200. It's a prety low standby draw unit yet can run a small shot vac.

travellerw
Member
# Posted: 26 Jul 2022 17:37
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Here is a link I promised.. This is pretty much what I built for our cabin, but I haven't really measured the power use yet (its on the list of things to do). However, I will say, that it cools down WAY faster than a traditional fridge. Even if we put warm stuff in it.

https://www.abdallahhouse.com/2018/08/super-fridge-upright-freezer-conversion.html

Brettny
Member
# Posted: 27 Jul 2022 10:29
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The digital temp controller they use in that is the STC-1000. Alot of guys that make there own beer do this conversion too. I'm sure they have a wright up some where if you wanted that info.

rachelsdad
Member
# Posted: 12 Aug 2022 04:17
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Sorry all. Long backpacking trip!!

I have 4 x 100 ah 24 volt Volts. Would like similar size 10 cf with freezer.

The propane unit just gobbles up fuel.

Notes, that is waaay over my head but good info to cut out the power hogs

Brettny
Member
# Posted: 12 Aug 2022 06:46
Reply 


You have roughly 200ah to use then. I dont see it running a 10cuft fridge for very long. Is this a weekend cabin? Do you plan on keeping the fridge going when your not there?

FishHog
Member
# Posted: 12 Aug 2022 08:14
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We bought a 10ft3 Unique dc fridge a few years ago to replace our propane one. Very happy with it. The only issue is it doesn’t self defrost as that function is a power sucker. If you put a lot of fresh veggies in it they give off a lot of moisture and the back wall frosts up. They recommend everything in sealed containers to avoid that.
Every few days I pull out the top shelf and use a plastic scraper to remove the frost which I chip into a container and transfer to my beer cooler

Otherwise it works very well and assuming you have solar to recharge you should be ok but I’d do a power audit first

paulz
Member
# Posted: 12 Aug 2022 18:45
Reply 


Quoting: FishHog
We bought a 10ft3 Unique dc fridge


That looks like a nice unit Fish. We are still using an ice chest size 12v fridge, it works great but no freezer and no shelves, which makes it kind of a pain digging everything out to get one thing. And I kill the power for the 1-2 days a week when we are not there, so it gets emptied frequently.

I wonder about going 110 AC on the next one though. I've slowly started using the inverter more and more for other things, don't leave it on all the time but I guess I could. Or maybe staying DC is more efficient?

gcrank1
Member
# Posted: 12 Aug 2022 19:18 - Edited by: gcrank1
Reply 


As loads get bigger the Inverter needs to get bigger, and with the cheaper inverters you cant trust the surge rating, they may only take a start up surge for a few seconds before tripping out, so you have to 'oversize' the inverter capacity....that means more watts eaten up by inverter even when idle.
This seems especially bad with the All In One units.
Straight DC wont have any of that.
Fwiw, I have an old 12vdc travel fridge that will also run off 120vac. The 120 is converted to 12 internally, inefficiency right there, and even worse if I invert from my 12v battery to 120vac thinking Im running the fridge on ac which it is not.
However, if one is overpaneled (ie, has elec production to 'burn'), it can still be worth doing it. If you are on the edge of keeping up with your loads, Id say no.

paulz
Member
# Posted: 12 Aug 2022 20:26
Reply 


Thanks G, good info. I'm overjuiced in solar right now but winter will be a different story as usual I expect, even though I've done some upgrading. We'll see. I'm good with keeping our current fridge at least until next spring.

travellerw
Member
# Posted: 14 Aug 2022 19:49
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Quoting: FishHog
We bought a 10ft3 Unique dc fridge a few years ago to replace our propane one. Very happy with it. The only issue is it doesn’t self defrost as that function is a power sucker. If you put a lot of fresh veggies in it they give off a lot of moisture and the back wall frosts up. They recommend everything in sealed containers to avoid that.


Those are really nice units and use quality components (pretty much same stuff used on most boats cruising southern latitudes). Just hard to swallow the price for most people. You do get what you pay for though.

The freezer conversion is close poor mans second, and you can use 110V to run it. Its actually surprisingly easy to implement. I bought the controller, put in an external plastic box and wired it to a standard house plug. I plug the fridge into that. Then I drilled a tiny hole in the back of the fridge to the interior and fed the temp probe in. Sealed everything with dollar store epoxy and done.

Let us know what you settle on!

paulz
Member
# Posted: 18 Aug 2022 20:51
Reply 


Quoting: FishHog
We bought a 10ft3 Unique dc fridge


Quoting: travellerw
Just hard to swallow the price for most people.


Hmm. Yeah not cheap but a few hundred off retail. Should I?
Screenshot_2022081.png
Screenshot_2022081.png


gcrank1
Member
# Posted: 18 Aug 2022 23:36
Reply 


I cant talk myself into it.
What size wiring does one of those require to deliver the 12v?
And how far? I would have to have it close to my charge controller 100' away from the cabin.
A re-worked 120vac chest freezer with some extra side shelving for easy access would be my choice. I can deliver 120vac to the cabin.

paulz
Member
# Posted: 18 Aug 2022 23:59 - Edited by: paulz
Reply 


Well after some measuring, it's too tall for my space without extensive surgery. They do make shorter units..

My current ice chest size fridge is 12v, on about 25' of 12awg, too thin probably. Draws 4 amps. It's packed with food right now and a pain to get to stuff. Need shelves..

Brettny
Member
# Posted: 19 Aug 2022 06:26
Reply 


Paul..I have less than that into my whole setup including the fridge and generator.

FishHog
Member
# Posted: 19 Aug 2022 08:02
Reply 


My unique draws 5 amps. I’m 5’ from my charge controller so wiring wasn’t a concern for me. You would have to do the math on a long run but you probably don’t want a 12v fridge if you have a long run

Yes they are expensive but for my small solar system and refusal to regularly hear a generator it was the right choice for me. But probably not the right choice for everyone

rachelsdad
Member
# Posted: 19 Feb 2023 17:41 - Edited by: rachelsdad
Reply 


"We have a 10.1cuft Magic Chef that is rated at 297kw/year, about .81kw/day. The big box store near our home in AZ has it for $328.00. Another forum memeber says his in actuality uses .50kw/day. That might help. Keep in mind that refrigerator only actually runs ~8 hours per day."

Brettny
Member # Posted: 12 Aug 2022 06:46
Reply Quote

You have roughly 200ah to use then. I dont see it running a 10cuft fridge for very long. Is this a weekend cabin? Do you plan on keeping the fridge going when your not there?[i][/i]


Boy life kinda got in the way!!

Just to clarify, I also have 9 Sunworld 260 watt solar panels. Spring to fall use...I looked up that unit NBD posted above. Same specs.

Would make life a lot easier but did I shoot myself in the foot going lithium?

As in: While my kwh has increased slightly by going to the Volt batteries, (4 x 1kwh x 80% DOD vs my old 8 6 volt 330 ah Trojans), I've lost boat loads of "capacity"????

I am adding two more Volts this spring for a total of 250ah

Doesn't seem right...or at least doesn't sound fair!

gcrank1
Member
# Posted: 19 Feb 2023 18:48 - Edited by: gcrank1
Reply 


Lead acid bats should not be drawn down past 50% of total ah capacity (and that capacity degrades over time so maybe they were only 80% of their 330ah?).
Do I remember you had them wired series/parallel for 24v?
I much preferred not going past 30% DOD for a quicker recovery/less stress/longer bat life.
Compare that to LFP that you can easily and regularly use 90% of capacity without harm. That means each LFP equals 3 LA by my math using the 30% or def equals 2ish LA if you use 50%.
How are you measuring your bat bank capacity? Voltage is notoriously poor to measure LFP.

rachelsdad
Member
# Posted: 19 Feb 2023 20:10
Reply 


Do I remember you had them wired series/parallel for 24v?

Correct

How are you measuring your bat bank capacity? Voltage is notoriously poor to measure LFP.

I was responding to the post I quoted by BrettNY that the 200 ah would be insufficient.

I'm about 6 weeks out from heading back up there and I have lots of projects....the mind is racing!!

Brettny
Member
# Posted: 20 Feb 2023 07:21
Reply 


Quoting: rachelsdad
How are you measuring your bat bank capacity? Voltage is notoriously poor to measure LFP.

I was responding to the post I quoted by BrettNY that the 200 ah would be insufficient

I have flooded lead acid batteries. I originally had 210ah of useable capacity, taking them down to 50%. I didnt want to take them that low so added another 105ah of capacity. That and another pannel made all the difference. I'm running a 4.5cuft fridge.

Make your first setup so you can add more battery and more pannel if needed. So dont cut your self short on charge controller. If you are going to cut your battery capacity very short get a shunt meter/battery monitor.

Nobadays
Member
# Posted: 20 Feb 2023 10:35
Reply 


I think maybe better to look at this in watt hours rather than amp hours.

Rachelsdad - 250ah @ 24v = 6000wh

With Brett... not sure of his set up but if I recall rightly he is using a 12v battery bank... correct me if wrong!

So Brett - now roughly 260ah @ 12v = 3120wh

Almost half the usable capacity of Rachelsdad's system. I think you would find that 6kw of storage @ .81kw/day is still going to give you ~7 days of running the fridge alone, likely more than that. With other draws I wouldn't speculate how long you could run without recharge, and but you will be recharging most days.

I know our original system was ~200ah @ 48v = 9600wh and we run not only the 10cuft refrigerator but also a 3cuft freezer continuously along with TV, internet, TV receiver, lights, etc.
Our only issue was we could not get more than 2 days without sun, hence we ended up doubling the size of the bank.

gcrank1
Member
# Posted: 20 Feb 2023 11:12
Reply 


Watt Hours, yes, I agree (though from my past history with vehicle wiring at primarily 12v I tend to automatically think in amps ) For small systems that works/is Ok but larger systems/demands thinking in Watts is better.
By talking in Wh's it avoids the confusion of diff voltage systems.
As the voltage goes up the amps loading goes down but the watts stay the same. V x A = W
As the amps loading goes down with higher voltage systems the smaller gauge wiring/fusing can be safely used and the lower the line losses over distance. This can be a huge cost savings! And smaller ga. wire is far easier to work with than larger.

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