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Freezer converted to low-cost fridge
#1
When I was participating at CRVL, I posted about a fellow in Australia who converted a chest freezer into a very low-cost refrigerator that could easily be run on solar.  His name is Tom Chalk of Mt. Best, Australia.  He bought a small energy-efficient chest freezer and changed the thermostat to turn it into a refrigerator that only takes 0.1 KWh of energy.  How much does a regular fridge that size cost to run?  Most people at CRVL seemed doubtful.

Here's the first article I saw on it, "A fridge that only takes 0.1 KWh?":  https://www.builditsolar.com/Projects/Co...fridge.pdf

Here is a more recent article about the conversion, "Freezer to fridge conversion":
https://mtbest.net/freezer-to-fridge-thermostat.html

And just today, I finally found a man who did it for his tiny house, it works as advertised, and he loves it!
"70 Year Old Builds Innovative Off-Grid Tiny House for Debt Free Retirement":
https://www.youtube.com/watch?v=n-K8l43sZgA

Would someone who understands electricity be willing to convert the draw of a common off-grid fridge or two (like a Domestic, etc) to the same language as this fridge, so it would be easy to compare the energy use?  Pretty please with sugar on it?
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  • Texjbird (09-12-2018)
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#2
I posted a thread on crvl about my low cost low power fridge.  

https://www.cheaprvliving.com/forums/sho...?tid=27624

The first paragraph is:
My efficient refrigerator uses very little electricity.  During the period of 10/1/17 through 11/2/17 the average consumption was 10.2 amp hours per day.  The highest 7 day period average was 12.13 amp hours per day with temperatures in the low to mid 90s.  The lowest 7 day period average was 6.78 amp hours per day with temperatures in low 70s to mid 80s.  This is actual in a van use, not an always cool place.  

To convert the numbers the math isn't too hard.  Mine is 13 amp hours per day.  Times 12 volts that's 13 amp hours × 12 volts =  156 watt hours per day.  156 watt hours divided by 1000 is 0.156 kilowatt hours per day.  

My fridge uses 8 pounds of water in ziploc bags in the freezer compartment.  It stays cold 3 days with no electricity.  I have a single group size 24 trolling motor battery for everything including engine starting, cell phone, fridge, leds, Maxxfan, etc.  Most people have substantial battery banks to keep the fridge cold for three days with no sun.
A sausage is only as strong as its weakest link.
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  • TWIH (09-13-2018)
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#3
(09-11-2018, 09:31 PM)TrainChaser Wrote: How much does a regular fridge that size cost to run?



Random WalMart 4.4 CuFt Fridge


[Image: 3e12794e-9d26-4c02-9aa6-b7e58d8a725b_1.6...nBg=FFFFFF]


226/365=.62 Kw/day

Someone told me once that household fridges had heating elements to keep freezer door seal defrosted, that's why little cheapy fridges, without those heaters, are so efficient.

Trebor, you're a thinking and doing sort!
Sometimes dweller in 236k miles '07 Grand C-van w/ a solar powered fridge and not much else
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  • TWIH (09-13-2018)
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#4
(09-11-2018, 09:31 PM)TrainChaser Wrote: Most people at CRVL seemed doubtful.

And not to be snide, or critical- Just an observation: Nearly anything NOT sold on Amazon, or avoiding an Amazon purchase got panned of that site.

My reasoning why would become critical, so I won't reason why, but I do believe my observation is accurate.

Just something to keep in mind when gauging their reactions to ideas.
Sometimes dweller in 236k miles '07 Grand C-van w/ a solar powered fridge and not much else
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#5
Thank you, All!

MC C Van: As with many things, follow the money! And cynicism balances blind faith. Somebody's gotta do it!
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  • MN C Van (09-12-2018)
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#6
(09-12-2018, 08:26 AM)MN C Van Wrote: 226/365=.62 Kw/day

Someone told me once that household fridges had heating elements to keep freezer door seal defrosted, that's why little cheapy fridges, without those heaters, are so efficient.

.62 kilowatt hours is 620 watt hours per day.  620/12=51.66 amp hours per day.  Add 20% for the inverter and you get 62 amp hours per day.  Depending on your location, climate, etc, 15 amp hours per day is a lot to expect from a 100 watt panel.  I wouldn't expect that 4.4 cubic foot to work with less than 400 watts of solar.  

Some household fridges have an electric heater in the door and a tube of hot freon in the main box going around the door opening.  

After the last hurricane I was starting generators so people could have their fridges running.  There was one that I started and was watching for a minute.  It was using 160 watts.  Then it clicked.  The timer switched off the compressor and turned on the automatic defrost heater.  That was 400 watts.  I didn't time it but it seemed like about 20 minutes.
A sausage is only as strong as its weakest link.
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  • MN C Van (09-12-2018)
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#7
The Oz Doc's is more efficient with a larger capacity than a Whynter.
65 qt is 2.2 cu ft. Half the size of the Danby 4.4. Uses much more than half the power.
Whynter's are not efficient, just smaller, so use less power.
Problem with a chest type is predefined floor space in an existing layout.
In a complete wall to wall conversion that would not be an issue.

I have a 4.4 cf Danby with no freezer compartment, as I only use a freezer to freeze water to carry on a longer hikes.

Early August Amargosa Valley in a van w/o shade. Shore power A/C only. No inverter. No solar. Door/lid shut during test. Similar contents.
Danby actual 24 hr watt hours 915.94
Whynter actual 24 hr watt hours 591.64
Standardize the Whynter to 4.4 cu ft, 24 hr watt hours would be 1,183.29
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  • TWIH (09-13-2018)
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#8
Seems like a small chest freezer should be way more efficient than a small dorm fridge due to the insulation and design..  The adjustable control device used to turn it into a non-freezer is available on Amazon for between $55 and $75, at least they were a few months ago when I looked them up.

As usual, I did nothing since I didn’t need refrigeration when I was in the Prius.  If/when I go out again, and if I had a van, I’d be willing to try the freezer.  Takes up a lot of room compared to a Donetic CF 28 though!
They say when you get older two things happen, one is you lose your memory and the other, I forget.

Organized people are simply too lazy to search for stuff.
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  • MN C Van (09-13-2018)
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