Is it necessary to run a refrigerator 24/7.....

K4KMG · September 2015

....or can it be shut off at night? For how long? On a timer? (full size fridge)

Photowhit · September 2015

Lots of opinions, but basically, yes.

They don't actually "run" continuously, but run like your air conditioner. A thermostat keeps food in a safe range of temperatures. Cycling times vary with the ambient temperatures of the environment the fridge is in....
... the warmer the environment the more they run..

Freezer conversions, run less since they have more insulation and loose their "cool", slower. Often you buy a thermostat for they that you select the safe range of temperatures, a feature rare in standard fridges.

K4KMG · September 2015

Thanks. Yes, I'm aware of the freezer conversions. Did quite a few back in the days I was brewing my own beer.
I'm currently in somewhat of a difficult situation. Had to move rather quickly to my off grid camp. RV fridge is not doing the job. I do have a full size regular fridge available, but my current solar setup is insufficient to add a fridge running 24/7. It will probably take me a month or two to upgrade the solar. In the meantime.........

Photowhit · September 2015

Vero Beach?

Might just get a cooler an large blocks of ice (single large blocks of ice, 15lbs or what ever they sell) they will last several days in a good cooler. Likely your cheapest alternative, unless you have an ice cream addiction.

K4KMG · September 2015

Photowhit wrote: »

Vero Beach?

Might just get a cooler an large blocks of ice (single large blocks of ice, 15lbs or what ever they sell) they will last several days in a good cooler. Likely your cheapest alternative, unless you have an ice cream addiction.

Actually 60 miles W of Vero. (k4kmg.com) This is probably a permanent situation. Yes, ice will get me through till solar is upgraded, but a real PITA!

Maybe I'll just go get the fridge and see what happens. (140 mi rd trip)

waynefromnscanada · September 2015

Consider that bacteria numbers can double every 20 minutes when some foods are allowed to reach room temperature, and also grow somewhat slower if allowed to be above 40F or below 140F, you should consider your health. Is a possible and preventable serious illness or worse, worth the risk to you?

K4KMG · September 2015

waynefromnscanada wrote: »

Consider that bacteria numbers can double every 20 minutes when some foods are allowed to reach room temperature, and also grow somewhat slower if allowed to be above 40F or below 140F, you should consider your health. Is a possible and preventable serious illness or worse, worth the risk to you?

Thanks. Decided to just leave well enough alone and upgrade solar sys to better handle the addition of my refrigerator.

lkruper · September 2015

K4KMG wrote: »

....or can it be shut off at night? For how long? On a timer? (full size fridge)

I had the same question for a different reason. I have a generator for emergency backup but would like a battery backup with a small inverter to keep light and electronics on at night and not run the generator all night. My thought process is that the power can go out for maintenance all day and the fridge/freezer stays cold so long as it is not opened frequently. But I do not know if repeating that every day would make a difference. I think 12 hours is enough to bring the temps back down but I have not tested it.

mike95490 · September 2015

Some fridges now use an electronic timer for the Defrost Cycle, and when the power is restored, it starts a defrost before it resumes cooling.

inetdog · September 2015

Unfortunately the bacteria in food do not respond to the average temperature. They make the most of the highest temperature they see to replicate like mad.
As long as the highest temperature reached is still low enough for food safety (~38F???) and you do not try to go below 32F on the cold end, you can make on/off cycling work (with the caveat mentioned by Mike about the defrost cycle.)
Instead of cycling the power on and off you could have two thermostats mounted in the fridge and switch between them based on the time of day. Leaning in the Rube Goldberg direction, but IMHO workable.
That way you could be sure that excessive door opening or other abnormal use patterns did not let the temp get too high during the setback period.

K4KMG · September 2015

Thanks all but I've decided not to screw around. Rack for 4 more panels, (picking up panels tomorrow), is about done and ordered a Morningstar Tristar 60 from NAWS. Batteries as soon as cc gets here. Luckily I have a Trojan dealer right down the street from me.

lkruper · September 2015

inetdog said:

Unfortunately the bacteria in food do not respond to the average temperature. They make the most of the highest temperature they see to replicate like mad.
As long as the highest temperature reached is still low enough for food safety (~38F???) and you do not try to go below 32F on the cold end, you can make on/off cycling work (with the caveat mentioned by Mike about the defrost cycle.)
Instead of cycling the power on and off you could have two thermostats mounted in the fridge and switch between them based on the time of day. Leaning in the Rube Goldberg direction, but IMHO workable.
That way you could be sure that excessive door opening or other abnormal use patterns did not let the temp get too high during the setback period.

That's a good point (the average temperature). What I had in mind was to power during the day with the generator and switch to a small battery bank at night to keep electronics on. Since it is at night, I don't plan on opening it. Also, in my case this would only happen if utility power failed and was not restored within one day, not a case of an ongoing practice.

oil pan 4 · September 2015

I was messing with my 2013 Kenmore full size normal fridge today, putting it on inverter/battery power and then intentionally left it unplugged for 3 hours. I put the flir on the inside contents after it had been off for 3 hours. The walls of the fridge were showing 40'F, the non reflective contents were showing between 33'F and 34'F.

In the freezer the ice was just starting to get a little wet.

lkruper · September 2015

oil pan 4 said:

I was messing with my 2013 Kenmore full size normal fridge today, putting it on inverter/battery power and then intentionally left it unplugged for 3 hours. I put the flir on the inside contents after it had been off for 3 hours. The walls of the fridge were showing 40'F, the non reflective contents were showing between 33'F and 34'F.
In the freezer the ice was just starting to get a little wet.

I just got a Frigidaire model that is supposed to work in an unheated garage or basement and had it installed in an unheated area. To work in cold weather they suggest setting the freezer to as low as possible. I think mine reads about 5 degrees. I wonder if starting out at a colder temperature would extend the time it can be unpowered.

oil pan 4 · September 2015

lkruper said:

oil pan 4 said:

I was messing with my 2013 Kenmore full size normal fridge today, putting it on inverter/battery power and then intentionally left it unplugged for 3 hours. I put the flir on the inside contents after it had been off for 3 hours. The walls of the fridge were showing 40'F, the non reflective contents were showing between 33'F and 34'F.
In the freezer the ice was just starting to get a little wet.

I just got a Frigidaire model that is supposed to work in an unheated garage or basement and had it installed in an unheated area. To work in cold weather they suggest setting the freezer to as low as possible. I think mine reads about 5 degrees. I wonder if starting out at a colder temperature would extend the time it can be unpowered.

When ever there was a bad line of thunder storms moving through or when I lived on the east coast and there was an incoming tropical storm or hurricane my parents would always turn the fridge down to its lowest settings. If the power went out, the fridge would be colder when the power went out. Making it take that much longer for the food to reach the food temperature danger zone.

hooperv · September 2015

I'm new here I hope I do this right.
Okey so I planned to run a mini fridge in my van. It has a proper separate freezer.
I was thinking of running it off of the solar during the day while freezing a bunch of 16 oz bottles of water. Then shutting it off at night after moving all the frozen bottles of water to the fridge section and placing them in and around any food. In effect using it like a cooler. The door would be closed all night.
Any thoughts from anyone?

bill von novak · September 2015

K4KMG said:

....or can it be shut off at night? For how long? On a timer? (full size fridge)

Sure. I can shut down the fridge in my garage for 4 hours at a time with no ill effects. There are refrigerators out there (often called DC vaccine refrigerators) that contain eutetic salts, so as long as they run about 4 hours a day they stay cold all the time.

oil pan 4 · September 2015

hooperv said:

I'm new here I hope I do this right.
Okey so I planned to run a mini fridge in my van. It has a proper separate freezer.
I was thinking of running it off of the solar during the day while freezing a bunch of 16 oz bottles of water. Then shutting it off at night after moving all the frozen bottles of water to the fridge section and placing them in and around any food. In effect using it like a cooler. The door would be closed all night.
Any thoughts from anyone?

I think the frozen bottles of water would last afew days before all the ice was gone.

Search "Insulin refrigerator" on the old evilbay to see examples.

lkruper · September 2015

hooperv said:

I'm new here I hope I do this right.
Okey so I planned to run a mini fridge in my van. It has a proper separate freezer.
I was thinking of running it off of the solar during the day while freezing a bunch of 16 oz bottles of water. Then shutting it off at night after moving all the frozen bottles of water to the fridge section and placing them in and around any food. In effect using it like a cooler. The door would be closed all night.
Any thoughts from anyone?

When you say "off the solar", do you mean to run without a battery bank? There are AC/DC fridges like Engel, ARB, and others than can run directly from a battery without an inverter, but I don't think even they will run directly from solar panels. A conventional AC mini-fridge (eg dorm style) fridge will also need to be able to handle a surge when the compressor starts up.

Also, if you are driving the van for any length of time, you will be able to power the fridge from your alternator and get a whole lot more power that way than from solar panels.

peakbagger · September 2015

There reusable freezer packs that contain a liquid that freezes at a lower temperature that will extend the period of time a freezer can be unplugged. I think Sundanzer offered an solar refrigerator that was lined with these freezer packs to compensate for periods of low light.

oil pan 4 · September 2015

Here is one guy that turned his fridge off for 6 hours at night.

http://ecorenovator.org/forum/appliances-gadgets/1448-test-results-power-savings-timer-fridge.html

cupcake · September 2015

look into inverter-compressor fridges.. times are changing and the DC motor is gonna run appliances now...

mah washer is a DC invertery motor type... DC motor ceiling fans are alreay here, and DC fridges are here and more are coming...
this means no more surge... a variable speed.. and more efficency...

again, research DC INVERTER MOTORS ...

inetdog · September 2015

cupcake said:

mah washer is a DC invertery motor type... DC motor ceiling fans are alreay here, and DC fridges are here and more are coming...
this means no more surge... a variable speed.. and more efficency...

again, research DC INVERTER MOTORS ...

At least in the case of the washer, it also means that it can use a direct drive motor with lots of poles around the circumference, eliminating the need for a multispeed gearbox and belts.

zoneblue · September 2015

They also now makeoff the shelf RV slash marine fridges that have built in salt packs. When the fridge detects its running on engine/solar it super cools the packs, then when the voltage drops, it turns the compressor way down.
It oughtnt be hard to do something like that with an arduino or something if yoru the DIY type.

2twisty · October 2015

I have my regular fridge on a timer.. Off at 11PM and on again at 6AM. NO troubles at all.

Make sure you have enough thermal mass in the fridge. I put a few gallons of water in the top to act as a thermal battery.

I also have a chest freezer that I turn off at 10 and back on again at 8. The stuff at the top of the freezer can get a little soft, so as long as you put stuff on the top that can handle some minor thawing and refreezing, there's no real problem there, either. Saves me enormous amounts of power this way.

Trickle Charge · October 2015

I had to buy a new fridge when I went off-grid. Ended up getting a Whirlpool that was EEE Tier 3 rated with a top freezer. Top freezers use 20% less power for some reason. It uses approx. 1.8 kWh/day.

inetdog · October 2015

Trickle Charge said:

Top freezers use 20% less power for some reason.

Better insulation and better air sealing have something to do with it.

K4KMG · October 2015

2twisty said:

I have my regular fridge on a timer.. Off at 11PM and on again at 6AM. NO troubles at all.

Perfect. Just what I needed to know. Thanks

Trickle Charge · October 2015

K4KMG said:

2twisty said:

I have my regular fridge on a timer.. Off at 11PM and on again at 6AM. NO troubles at all.

Perfect. Just what I needed to know. Thanks

Isn't it just going to use up as much or more power during the day to make up for the temp loss overnight? My freezer works harder when I put stuff in it as opposed to when it just maintains a temp.

westbranch · October 2015

Trickle Charge said:

I had to buy a new fridge when I went off-grid. Ended up getting a Whirlpool that was EEE Tier 3 rated with a top freezer. Top freezers use 20% less power for some reason. It uses approx. 1.8 kWh/day.

We got this model in May, GE Model GTE18GMHDRES 319 kWh Canada/ 358kWh US and it uses about 60-75% of the 319kWh per year in the summer 75% = ~ 240KwH/YR / 365 =~ 656 W/day

mike95490 · October 2015

summertime, my freezer in the garage runs 24/7, but in winter, I put it on a timer, and shut it off 2am - 9am, to save the batteries a bit. Last year we had 4 or 5 cloudy weeks in a row, lots of generator run time.

Is it necessary to run a refrigerator 24/7.....

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