A possible way to keep your fridge cold in long term blackouts.

[msuffidy]

So where I live I have never seen a blackout in 17 years last longer than 2 hours. We are getting a lot of bad storms and I was just even considering the problem.

Originally I thought what may be actually the most 'efficient', like in terms of input to output power, would be to modify a fridge compressor so it could be fed from a belt. The belt would connect to some sort of rotating power source, like a bike, or windmill.

Then I was thinking the most normal and easy way to do it is to get a power bank of some sort with a 120V inverter.

In this video it seems to do most of the things you need.


So I have the following sort of questions.

1) Provided a fridge is not all the time, but is on some of the time, can you humanly input the same power as a fridge uses (different if not started warm)?
2) With 120V inverters are there power losses when appliances are idle or disconnected?

So in conclusion based on the fact it does not happen here and I don't have a lot of value in terms of loss in my fridge, I think I am just going to ignore the problem.

[bob91343]

I have come to the same conclusion.

[Someone]

1) Provided a fridge is not all the time, but is on some of the time, can you humanly input the same power as a fridge uses (different if not started warm)?

No
Typical residential fridge+freezer, 300-400kWh per year:
https://www.energyrating.gov.au/calculator

Most humans are unable to produce 100W continuously:
https://en.wikipedia.org/wiki/Human_power

1kWh/day at least 10 hours continuous human effort

[Someone]

So could that much energy be supplied by human power?  Yes, probably.

Please demonstrate this! You won't be able to.

[antenna]

Crosley Icyball

[Someone]

So that's coincidentally almost exactly 1kWh / day, which translates to 41.7 Watts per. hour average --
and I believe these are likely normal usage numbers involving opening / closing the unit often, adding new items to be refrigerated, making ice, things one could cut back on during a power outage.

On a typical leisurely workout I easily sustained more than 41W output according to my exercise bicycle so truly it could
be done even manually on a generator bicycle.

24 hours a day continuous activity? Again, feel free to demonstrate this, do make a video of you providing 1kWh a day. 99% of the population will fall over spectacularly.

[msuffidy]

It sounds for a typical fridge it is close. Maybe a smaller one could be used for critical things.

[Someone]

And of course one can buffer excess in a battery to avoid needing to be quite so continual.

24 hours a day continuous activity? Again, feel free to demonstrate this, do make a video of you providing 1kWh a day. 99% of the population will fall over spectacularly.

It doesn't matter how perfectly you can capture and level the energy, 1kWh per day is outside the range achievable by most people. Its off into performance athlete territory. One of the often reproduced graphs on the topic is included below with a 1kWh/day locus. Feel free to come up with some data points that do sit above that locus, they're all going to be high performance athletes in the 0.00... something percent.

[sleemanj]

Typical residential fridge+freezer, 300-400kWh per year:

Poster asked about a fridge, not fridge+freezer.

You can get standalone fridges that need half of that power easily.

[Someone]

Typical residential fridge+freezer, 300-400kWh per year:
https://www.energyrating.gov.au/calculator

Poster asked about a fridge, not fridge+freezer.

You can get standalone fridges that need half of that power easily.

When consumer says fridge they almost always mean a 2 door fridge+freezer combination, hence the direct link to the data source which surprise surprise calls a 2 door fridge+freezer, a "fridge". You could take all sorts of obnoxious interpretations of "fridge" but even a leading efficiency fridge only domestic unit still needs 400Whr/day:
https://reg.energyrating.gov.au/comparator/
Unless you want to start walking this to a silly point like a tiny "cold" wine fridge/humidor.

[Someone]

To be precise I don't really agree with your statement that it is necessarily outside the range achievable by most people, rather a more likely correct statement would be that it's well outside the range *achieved* by most people between their late-teen years and middle age.  Clearly it wouldn't be productive to consider "most people" numerically including infants, toddlers, octogenarians, et. al.

But "performance athlete" level endurance with moderate strength / power output anyway is precisely what we're mostly all genetically / biologically "equipped" to be able (biologically) to achieve (given suitable prerequisite fitness conditioning).

Nomadic physically active lifestyles, surviving harsh conditions without technology, struggling physically just to survive vs.
predation, starvation, migration, etc.   Consider what may have been a much more "average person" level of fitness 13ky-1My ago for a hominid vs. today.   So with regular exercise / effort I wouldn't be at all surprised if the "average" young/mid-adult could become fit to achieve / well exceed that output power for 12-18 hours anyway with sleep becoming a barrier past that.

It is after all an "endurance" level of power output so like running a marathon (which is routinely done by young and old even not-so-performance-athlete types) it's mostly about a baseline level of cardio fitness and then sheer willpower and routine.

Provide some data points, human endurance falls off a cliff very quickly. What someone can do for an hour or two cannot be extrapolated out to all day long. 1kWh/day is Tour de France level endurance, not something that is achievable by normal people. You might be able to train some percentage of the population to do this, but that's not the question (having done endurance sports with people who wanted to do it, I can tell you normal people fall over and collapse when pushed to do that level of performance).

From the graph you cited the required level of fitness to generate -- asymptotically -- an energy production rate meeting 1kWh/day
is actually under the curve of "NASA curve for healthy men" implying to me that normally healthy men should be able to do that for
say 55W/18h or maybe 41.7W average / 24 hours or some other power-time integral that meets the energy production rate.
That isn't seeming to say it is only achieved by uber-athletes, though being able to do that and still get sleep normally and carry that on beyond 24 hours is clearly challenging due more to the "down time" of sleep than the actual endurance level wattage needed.

The 1kWh/day locus is not under "NASA curve for healthy men" at any point, that is an extrapolation of amateur athletes from another data set and might meet it at the single day 24 hour endurance point (that doesn't include a repeat performance for ongoing power outage). So an amateur athlete might be able to do 1 day of that power level, and fall over collapsed at the end of that effort.

How much more wrong do you want to be?

[sleemanj]

When consumer says fridge they almost always mean a 2 door fridge+freezer combination

1.  This is EEVBlog, engineers should define things in specific terms.
2.  If I go to buy a fridge, I'm buying a fridge, not a fridge freezer, if I wanted a fridge freezer I would ask for a fridge freezer
3.  While fridges are less common these days, they are still readily available...
 
Harvey Norman, who I think you have in Australia also, sells a number of them...

130-238kWh Refrigerators

That's not to say that it's not a silly idea to directly run a fridge from a bicycle **directly**, it is an obviously silly idea, the consumption of a fridge is not constant, it needs a large amount of power for a short amount of time and the human is woefully under equipped to provide the peak demand.

However, riding a bike charging a battery bank and running the fridge from said battery bank, we are probably achievable, for the sake of argument let's take the 130kWh fridge, about 356 Watt hours a day requirement, let's assume you can comfortably produce on your bicycle 25W continuous, might be possible, especially if you have a couple of people swapping every hour or so.

Even on your own you only have to cycle for about 14 hours a day, leaving 8 hours for sleeping and a couple hours for limping around wishing you'd bought a solar panel or generator instead of macguyvering your Raleigh 10 speed.

[Someone]

When consumer says fridge they almost always mean a 2 door fridge+freezer combination

1.  This is EEVBlog, engineers should define things in specific terms.

Which is why I was explicit "fridge+freezer" and shared the data sources (unlike everyone else). If you want criticise or poke holes then why pick out the accurate and referenced posts?

If people want more data... typical domestic refrigeration per household in Australia was over 2kWhr/day:
https://renew.org.au/renew-magazine/efficient-homes/unravelling-home-energy-use-across-australia/
That lumps combined fridge+freezer units together as "refrigerators" with a separate category for freezer only. Fridge only is so unusual it doesn't make a mention. Original source of the data is difficult to find, but it looks like that was from an earlier revision of "Residential Baseline Study 2015".

Typical household food storage energy use does not overlap with the typical household human power capability. There is some small double corner case of endurance athletes + small/few/efficient appliances, but even then its still needing a ridiculous amount of time/effort dedicated to keeping food cool and doing little else.

[BrianHG]

Example log of  usable power from a treadmill motor rigged to a stationary bike before I broke my lower back:

Code: [Select]

logs\BikeBrake_05-11-2011_20h16m09s.raw   1:10:09.3     76.15
logs\BikeBrake_05-13-2011_14h12m10s.raw   1:10:07.0     88.05
logs\BikeBrake_05-16-2011_11h31m29s.raw   1:10:10.3     94.37
logs\BikeBrake_05-19-2011_08h34m19s.raw   1:10:08.3     92.38
logs\BikeBrake_06-19-2011_15h28m41s.raw   1:10:13.9     99.89
logs\BikeBrake_06-20-2011_12h35m14s.raw   1:10:10.2     91.49
logs\BikeBrake_06-21-2011_11h06m35s.raw   1:12:44.0     99.88
logs\BikeBrake_06-22-2011_12h24m06s.raw   1:10:06.0     101.35
logs\BikeBrake_06-23-2011_10h46m00s.raw   1:10:11.3     100.46
logs\BikeBrake_06-30-2011_16h42m45s.raw   1:10:08.0     100.60
logs\BikeBrake_07-02-2011_13h44m35s.raw   1:10:13.6     97.37
logs\BikeBrake_07-04-2011_10h47m49s.raw   1:10:09.0     102.89
logs\BikeBrake_07-05-2011_11h44m08s.raw   1:10:10.0     104.29
logs\BikeBrake_07-10-2011_12h56m26s.raw   1:10:08.6     101.98
logs\BikeBrake_07-11-2011_16h36m57s.raw   1:10:12.9     97.06
logs\BikeBrake_07-18-2011_13h12m12s.raw   1:10:09.1     100.71
logs\BikeBrake_07-20-2011_14h00m53s.raw   1:10:12.4     100.42
logs\BikeBrake_07-24-2011_13h41m13s.raw   1:10:20.2     103.44
logs\BikeBrake_08-01-2011_15h37m30s.raw   1:10:10.9     100.62
logs\BikeBrake_08-03-2011_13h47m30s.raw   1:10:11.3     104.12
logs\BikeBrake_08-04-2011_18h02m08s.raw   1:10:15.8     95.95
logs\BikeBrake_08-09-2011_12h59m31s.raw   1:10:14.7     104.57
logs\BikeBrake_08-18-2011_14h22m33s.raw   1:10:14.3     97.13
logs\BikeBrake_08-20-2011_16h52m49s.raw   1:10:10.5     96.79
logs\BikeBrake_08-22-2011_16h52m24s.raw   1:10:11.0     95.79
logs\BikeBrake_08-23-2011_14h59m23s.raw   1:10:06.5     93.97
logs\BikeBrake_08-28-2011_18h03m05s.raw   1:10:13.7     95.18
logs\BikeBrake_09-06-2011_14h59m03s.raw   1:10:14.0     90.67
logs\BikeBrake_09-11-2011_16h45m30s.raw   1:10:16.3     94.06
logs\BikeBrake_09-16-2011_17h30m48s.raw   1:10:15.0     101.04
logs\BikeBrake_09-18-2011_18h15m57s.raw   1:10:16.3     96.54
logs\BikeBrake_10-06-2011_10h59m14s.raw   1:10:33.8     86.90
logs\BikeBrake_10-10-2011_14h31m06s.raw   1:10:23.4     96.37
logs\BikeBrake_10-11-2011_14h32m33s.raw   1:10:14.6     100.29
logs\BikeBrake_10-22-2011_21h05m47s.raw   1:10:13.6     87.47
logs\BikeBrake_10-26-2011_17h27m12s.raw   1:10:08.3     82.98
logs\BikeBrake_11-04-2011_19h48m32s.raw   1:10:11.0     83.67
logs\BikeBrake_11-19-2011_20h21m35s.raw   1:10:15.0     87.35
logs\BikeBrake_11-21-2011_20h29m18s.raw   1:10:13.9     88.13
logs\BikeBrake_12-05-2011_11h36m14s.raw   1:10:13.3     76.95
logs\BikeBrake_12-07-2011_09h22m58s.raw   1:10:14.6     87.37
logs\BikeBrake_12-16-2011_11h47m23s.raw   1:10:22.3     87.33
logs\BikeBrake_12-18-2011_21h37m56s.raw   1:10:46.6     71.83
logs\BikeBrake_12-19-2011_20h31m55s.raw   1:10:20.1     75.96
logs\BikeBrake_12-29-2011_01h30m36s.raw   1:10:14.6     70.85
logs\BikeBrake_12-29-2011_15h31m58s.raw   1:10:19.7     85.47
logs\BikeBrake_01-01-2012_18h24m41s.raw   1:10:11.5     82.06
logs\BikeBrake_01-02-2012_23h40m48s.raw   1:10:21.0     75.89
logs\BikeBrake_01-03-2012_14h48m30s.raw   1:10:08.2     89.10
logs\BikeBrake_01-06-2012_00h08m40s.raw   1:12:28.3     91.47
logs\BikeBrake_01-09-2012_13h01m36s.raw   1:10:08.7     88.87
logs\BikeBrake_01-11-2012_19h10m47s.raw   1:10:11.7     94.32
logs\BikeBrake_01-14-2012_04h15m45s.raw   1:10:08.2     82.67
logs\BikeBrake_01-15-2012_03h09m43s.raw   1:10:12.4     81.97
logs\BikeBrake_01-16-2012_14h10m47s.raw   1:10:13.3     92.30
logs\BikeBrake_01-18-2012_14h23m24s.raw   1:10:12.5     92.82
logs\BikeBrake_01-19-2012_16h36m15s.raw   1:10:11.2     94.84
logs\BikeBrake_01-24-2012_18h00m16s.raw   1:10:14.1     86.09
logs\BikeBrake_01-27-2012_21h35m06s.raw   1:10:13.1     80.81
logs\BikeBrake_01-28-2012_16h19m43s.raw   1:10:16.9     95.11
logs\BikeBrake_01-30-2012_15h49m53s.raw   1:10:11.4     93.37
logs\BikeBrake_01-31-2012_13h51m08s.raw   1:10:10.1     96.24
logs\BikeBrake_02-01-2012_16h09m28s.raw   1:10:09.7     93.08
logs\BikeBrake_02-04-2012_21h23m43s.raw   1:10:13.6     88.37
logs\BikeBrake_02-06-2012_19h30m21s.raw   1:13:33.4     94.25
logs\BikeBrake_02-07-2012_18h22m55s.raw   1:10:07.9     97.75
logs\BikeBrake_02-16-2012_20h55m57s.raw   1:10:16.5     91.16
logs\BikeBrake_02-18-2012_09h27m13s.raw   1:10:11.5     93.05
logs\BikeBrake_02-20-2012_03h36m49s.raw   1:10:14.2     87.21
logs\BikeBrake_02-22-2012_07h04m19s.raw   1:10:16.9     101.13
logs\BikeBrake_03-04-2012_09h29m26s.raw   1:10:14.8     90.05
logs\BikeBrake_03-08-2012_14h48m36s.raw   1:10:12.0     91.71
logs\BikeBrake_03-09-2012_13h29m48s.raw   1:10:10.3     91.68
logs\BikeBrake_03-11-2012_13h28m52s.raw   1:11:03.5     93.60
logs\BikeBrake_03-14-2012_11h28m55s.raw   1:10:10.4     95.04
logs\BikeBrake_03-20-2012_14h26m45s.raw   1:10:08.5     90.43
logs\BikeBrake_03-22-2012_17h51m00s.raw   1:10:13.6     80.35
logs\BikeBrake_03-26-2012_11h08m58s.raw   1:10:09.1     92.26
logs\BikeBrake_04-01-2012_12h51m17s.raw   1:11:52.7     93.29
logs\BikeBrake_04-08-2012_12h49m27s.raw   1:10:11.8     96.27
logs\BikeBrake_04-09-2012_12h56m02s.raw   1:10:23.2     96.09
logs\BikeBrake_04-10-2012_14h00m14s.raw   1:09:43.7     89.43
logs\BikeBrake_04-13-2012_12h09m35s.raw   1:10:07.4     91.89
logs\BikeBrake_04-18-2012_16h30m32s.raw   1:10:12.3     98.31
logs\BikeBrake_04-22-2012_02h17m41s.raw   1:10:25.1     91.99
logs\BikeBrake_04-24-2012_16h13m45s.raw   1:10:08.8     93.04
logs\BikeBrake_04-28-2012_14h41m58s.raw   1:10:31.0     86.68
logs\BikeBrake_05-01-2012_13h21m44s.raw   1:26:09.8     102.90
logs\BikeBrake_05-03-2012_14h12m54s.raw   1:26:14.1     102.70
logs\BikeBrake_05-06-2012_09h04m57s.raw   1:26:17.1     103.71
logs\BikeBrake_05-07-2012_08h05m04s.raw   1:26:17.0     102.40
logs\BikeBrake_05-09-2012_19h12m18s.raw   1:10:14.4     84.59
logs\BikeBrake_05-12-2012_11h53m24s.raw   1:42:08.4     122.16
logs\BikeBrake_05-15-2012_11h20m21s.raw   1:42:18.3     125.05
logs\BikeBrake_05-19-2012_17h51m19s.raw   1:10:14.0     79.32



Format: date of workout - time when workout began - length of workout (includes 10 min warmup) - total surplus power sent into halogen bulbs over the time period.

After friction, belt, poor efficiency of using the treadmill motor at too low an RPM and as a generator, I'm guessing I was applying approximately double the wattage at the pedals.

Time to get modern power-meter pedals, mount them on my exercise bike to see how truly efficient my generator setup is so that I can see how well I actually performed.

[BrianHG]

I've a .png (graph color shows software gears, white = watts, green = pedaling rpm) of a workout graphs from my bike hardware and an old image of my bike hardware before I created the solid state control electronics.

The exercise micro-v-groove belt made the entire system silent.  In that image, the transformer was a resistor.  The electronics which generated the workout graphs removed the old transformer / switches for full PC with PWM control for software gearing and logging.

[Someone]

I think it depends on the particulars.
For instance as the poster is flying a Canadian flag I might assume they're in Canada and not Belize, so the *actual* energy required could be quite different.

You bring up a huge volume of "but but but" and it all falls flat:
"Energy Consumption of Major Household Appliances Shipped in Canada" data up to 2018 shows "standard sized" "refrigerators" are over 1kWh/day except for the smallest category: https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/menus/aham/2014/tables.cfm

Even 2 fit adults will be flat out or unable to meet that level of power demand. As I said, people powering food cooling is a corner case convergence of very fit people in the household and a small/efficient fridge simultaneously. Even that optimistic case only just gets there with little time/energy to do anything else. You can't just keep chipping away at the edges to suddenly make the basic premise true, you're hunting some bizarre outlier that is not representative of the population. This isn't even a close run thing, its plainly impractical.

[Someone]

After friction, belt, poor efficiency of using the treadmill motor at too low an RPM and as a generator, I'm guessing I was applying approximately double the wattage at the pedals.

Time to get modern power-meter pedals, mount them on my exercise bike to see how truly efficient my generator setup is so that I can see how well I actually performed.

Thanks for the picture, 50% efficiency from that is probably a pessimistic figure. Belt drive to a small (DC permanent magnet?) motor/generator like that is probably around 70% or more.

[BrianHG]

Those box-style fridges or deep-freezers where the door is at the top and open vertically use around half of the energy for freezing, around 1/3rd for refrigeration compared to the normal ones we use in our kitchens.  This has to do with the quality of the perfect unbroken insulation with the seal only around the top as these fridges were designed specifically for long term storage, low power consumption.

So, with a really efficiency  bike/generator combo, a LifePO battery pack as your capacitor, and a comfortable just around 100watt pedaling, you might get away with 2 adults willing to sacrifice around 3-4 hours a day each, that is unless you are both Tour-de-France grade riders who can sustain 400 watts for 1 hour straight.

Note that if you never open the fridge or add new food, maybe it will require a little less power.

[BrianHG]

Belt drive to a small (DC permanent magnet?) motor/generator like that is probably around 70% or more.

I was running a 125v motor generating  15v at around 6 amps of current, around 10% of the designed RPM.  And if you look at permanent magnet DC generators, at low RPM, their efficiency drops off an edge like a cliff.  I would need to pedal at 5x my usually speed to get anywhere near the 70% efficiency, 10x to be in the motor's designed spec.  At proper RPM, voltage and current, the theory is around 83% efficient for a tuned DC brushed motor.

I needed another layer of gearing to achieve any good efficiency.

However, power-meter pedals would tell me the truth, except they are pricey for some good ones with the combination of having to buy biking shoes.

[Someone]

You seem to be arguing for the sake of argument to try to prove me wrong or something which is odd since it was only as an theoretical aside that I (and presumably the original poster) mentioned the possibility (not practicability or desirability) of human power.

In the face of quality referenced figures, you keep posting up easily proven incorrect statements. Just because some of (your overly longwinded and dithering) posts contain some things that are true, you're still majority plainly wrong and digging in on them.

Do continue to walk this off to some imaginary place where endurance athletes are suddenly equipping their houses with speciality food cooling equipment for the purpose of emergency situations.....  except anyone with any sense would be getting a gas powered fridge for that, as already hinted at:

Crosley Icyball

Humans produce very little power, but you keep trying to push that out and say my very carefully framed and referenced figures are wrong. They're not. You guess at the population having lower power consumption, make no effort to check, and in the face of actual figures for the actual location you questioned, go on arguing how you are still right (in some new and even less believable frame)

[tszaboo]

The last thing you want to do in case of an extended blackout is start a workout that you are not prepared. That is a sure way to die of hearth attack while waiting for the overloaded ambulance to arrive.
Just have a 12 pack of canned chicken soup in the garage. Maybe some MRE. Some canned food. Few bottles of water. Something that can cover your preferred "time without services". For me it is a week.
Eat/drink the stuff that's about to expire and buy new. This is not rocket science.

[sleemanj]

hearth attack

Got to be careful of hearths.

[tooki]

FWIW, one key to having a fridge keep cold when unpowered is to keep it full. The thermal capacity of the air in the fridge is minimal. So fill any spare space with bottles of beverages. Once they’ve cooled initially, they don’t need any extra energy to keep cold.

This also improves the energy efficiency of a fridge or freezer in everyday use, because the volume of cold air lost in everyday use is reduced. (So yeah, keep ice packs in your freezer if you tend to not store much.)

[Refrigerator]

IIRC an old school synchronous fridge compressor is rated around 160W. An induction motor is more-less a constant speed motor so if you don't supply enough power it will slip/stall, so let's keep that in mind.
To make it work you would need an inverter, a pure sine one at that, and some kind of way to stabilize the energy you produce by pedaling with some kind of battery or capacitor bank.
Most good quality pure sine inverters are rated above 85% efficiency (i checked) so let's take 85% as our efficiency, assuming worst-case scenario given the unstable power production.
So the sine inverter would need 188W of power just to run the fridge.
Add the inefficiency of your generator setup and ask yourself can you really produce this amount of power by pedaling?
Also let's not forget that fridges don't run constantly, rather they run only when they need to, so if you connect to the compressor directly, your pedaling would directly affect the temperature inside the fridge.
You could also use some kind of energy storage solution (battery bank or whatever) to produce energy by pedaling now and let the fridge use it later, but then you would have to add the charge-discharge inefficiency on top.
Serious cyclists often measure the power they produce and you might be inclined to use these numbers for estimations but we have to keep in mind that cyclists have the benefit of airflow to cool them down and the ones that care about their performance tend to me more athletic.
Unlike the average Joe, who would be sweating their ass off while pedaling indoors just to keep their beer cold 

[Alex Eisenhut]

The best you can do is make sure the magnetic seals are clean, and keep a few jugs of ice in the freezer to transfer to the fridge in case of a long blackout.

Keeping the freezer full,as noted, is a good idea, and since I don't usually keep much frozen foodstuff I keep it filled with ice.