Using a 120 vac Dorm Fridge

[fraz627]

Is it possible to use a 120 v Dorm Fridge off a 2000 watt invertor. My research shows that it has been done but cannot find the power draw.

All advice is welcome.

Jim

 

[fraz627]

Thanks It just seems less expensive than the other options.

 

[B and C]

What you lose in efficiency with the 12V fridges you will have to make up with more solar and battery as well as invest in a inverter. Everything is a trade off.

 

[highdesertranger]

yes it might work for you, for me it did not work. I tried every type of refrigerator and cooler trying to save the cost of a 12v refrigerator. I thought 12v refrigerators were to expensive. if I would have just bought a 12v to begin with I would have been dollars ahead, all that money I wasted trying to save a buck. highdesertranger

 

[tx2sturgis]

I did exactly this.

It worked well, with some experimentation...and I like the fact that if it stops working, you can replace the $100 fridge, rather than shell out another $500 or more for a 12v fridge. Some of these only seem to last a few years in full-time use. 

I purchased a 1.7 cu ft energy-star dorm fridge that has a mechanical thermostat (not digital or electronic)

I powered that with a GoPower 700 watt PSW inverter...and this inverter has a power-saving 'sleep' mode....so it essentially shuts itself off when the fridge thermostat is not calling for cooling. This is fairly important if the power source is solar.

I used a 110 ah AGM battery and 200 watts of solar.  

Since these fridges are not designed for mobile use, you need to figure out a way to keep the fridge door shut when driving. I used a combination of velcro and a really huge rubber band...lol...yep it worked! Also most of these small fridges have a 'skin condenser' so you cant enclose them in a cabinet, or wrap additional insulation on the unit, and neither do you want the sun shining thru an open door or window on the fridge.

If the solar panels are flat mounted on the roof, winter-time power production will drop off (lower sun angles and shorter days) and if you are in a cold climate, this will probably work ok, but if you are in the south, in a warm climate, you might need to tilt the panels or use a small generator to 'top-off' the batteries during days of cloudy/rainy/snowy weather.

Obviously, doubling or tripling the solar output should provide all the power that the fridge will need and lots of surplus for other uses.

 

[wayne49]

The main issue with AC fridges designed for 68-72 degree indoor usage is when the ambient air temp is far enough out of that 68-72 range, the fridge temp varies far from normal, and either freezes contents that shouldn't be frozen or the temp rises above safe food handling temps. The compressors are not designed to be running for extended periods.

Night time below freezing, afternoon too warm.

I like the Whynter AC/DC units, they have a digital temp setting for consistency in unconditioned air usage. I have a 62 qt in an non-insulated cargo van and a 45 qt in a class C motor home.

One other point about compressor fridges, they have automatic defrost cycles in which the coils are heated, then obviously cooled back down. Okay when hooked to shore power, wasteful otherwise.

 

[tx2sturgis]

One other point about compressor fridges, they have automatic defrost cycles in which the coils are heated, then obviously cooled back down. Okay when hooked to shore power, wasteful otherwise.

Most of the small dorm fridges don't have a defrost cycle. There is no timer or heating coils. Otherwise, what you posted is certainly relevant....they are generally designed for normal living space temperatures, but I found the temps inside the freezer portion to be, good enough, even when ambient temps varied a lot. The little 'chiller' sections are so small anyway, unless you buy a dorm fridge that is in the 3-6 cu ft range.

With a small dorm fridge you can keep a few dinners frozen for a few days to maybe a week, and maybe make a tray of ice cubes, but you wont be keeping 2 gallons of ice cream, a package of 24 popsicles, and a 10 pound bird safely frozen for months, that is for sure.

Maybe not the BEST option...but they are AN option...and if you already own one, go for it.

 

[highdesertranger]

I run one of my Engels as a freezer on 12v. I still have stuff in there from 2 1/2 months ago. everything is fine. this way I can resupply when I am in good shopping areas, of which I am not at now. highdesertranger

 

[tx2sturgis]

I ran my Dometic 12v fridge in freezer mode for about a month. They use a good amount of electricity in that mode, the compressor runs often and sometimes for long periods during hot weather. 

But they do work well for that.

 

[highdesertranger]

what I do is put what I want frozen in there and turn it all the way down for 12-24 hours depending on ambient temps.
in this mod it runs almost constantly but it uses so little power I hardly notice.
once everything is frozen like a rock then I turn it back up.
on an Engel there is no digital read out. there is a dial like you had in older refrigerators the dial goes from 1-6, with 6 being the coldest.
so I turn it from 6 to 3. this keeps everything frozen rock hard and use only slightly more power that the ones I use as refrigerator.
on refrigerator mode I keep it at just over 2. you must be careful to stay away from 3 or everything will be frozen. I have done this more than a few times.

speaking of which does anyone know of a decent remote thermometer? I use a failsafe ice cube in my freezer now but would like to know at a glance what's going on.

highdesertranger

 

[highdesertranger]

thanks Sofi, is that what you use. I think I looked at those before but I got scared because of all the bad reviews. highdesertranger

 

[highdesertranger]

thanks. highdesertranger

 

[B and C]

I use one similar to this (same brand, etc): https://www.amazon.com/AcuRite-Digi...d=1595256861&sprefix=accurite,aps,203&sr=8-10

I just put the outdoor sensor in the fridge. I velcroed the readout part to the wall by my door. Sensor batteries may only last a couple of months at freezer temps though.

They do make more expensive ones with alarms.

 

[wayne49]

The basic take away about "dorm" fridges is where you spend your budget.

HDR mentioned this issue. I also went through the exercise of throwing dollars away trying to avoid purchasing a "pricey" purpose built 12V DC fridge.

I even developed a digital fridge controller to turn the inverter on and off in a precise temp range. The ON cycles at higher temps would be greater than the OFF cycles, abusing the light duty compressor, I'm sure.

Both Whynters that I own have never had an issue with maintaining internal temp at air temps in the 100 to 110+.

Buy a cheap AC fridge, then spend more on a larger battery bank, more on a quality inverter, and more on a larger solar setup to feed the larger bank.

Or spend more on a purpose built 12V DC fridge then buy a smaller bank and a smaller solar setup.

 

[DLTooley]

If I was to go that route I’d choose a used one for clear cost savings.

 

[highdesertranger]

" I’d choose a used one for clear cost savings."

you think so, that is exactly what I did. what a waste of money. what about all the wasted food because it doesn't keep a stable inside temp.

highdesertranger

 

[Jimmyflorida]

Is it possible to use a 120 v Dorm Fridge off a 2000 watt invertor. My research shows that it has been done but cannot find the power draw.

All advice is welcome.

Jim

I did this in a semi truck before but I drove 700 miles a day and was fine but would run the batteries down if not running for 3 or 4 days I dont really think it's worth trying there are cheaper 12 volt compressor options for not that much more than the dorm fridge just my 2 cents