I repair powerlines for a major utility, people always stop me(while I'm in the process of restoring power mind you) and ask how long it'll take because they don't want their food to go bad. I understand their concerns. I also like having my power on. So I can't wait to send them here.
I really appreciate you linemen! We have many outages a year (usually due to weather and falling trees). You folks get on the job very quickly no matter how bad the weather. For that I am grateful! Cheers!
Quick story. We were working a storm a few years back. We we're on our 8th day of 18 hr days(yeah, it's doubled bubble), this little tiny old lady pulls up while I'm booming down to get more supplies. So I hear this encounter. She wants to know when the power is coming back. She has meat in the freezer and is concerned. If she was anything like my own grandmother it was probably a single hamburger, slices from a left over ham, and one individually wrapped hotdogs. The groundman tells her a few hours to most 10 hours. It was an ice storm... an act of God... anyway we felt bad for her but there was 8 hrs of work... so she starts yelling at us. Now, she probably never did a day of hard work and she's yelling at guys that have been working 18hrs a day for about 8 days straight, climbing pole covered in ice and stuff, right... which is fine. Seriously none of us mind getting yelled at by lunatics. It's part of the job. So when she goes to drive off she yells "My meats gonna go bad" as if we were directly to blame and not helping the situation. My co-worker says as a matter of fact but not so she could hear "Lady, your meat went bad a long time ago." Funniest thing ever. I laughed for the rest of the day. I still drive around and remember it and laugh. Whenever my wife is concerned about leftovers not getting eaten I'll say "lady, you're meat..." "Enough! Not again. Just eat the food" So that's my story.
I am getting proper wiring out to my shed soon and I was worried about how long the frozen stuff would last before it warmed up too much. Your psychic abilities are definitely improving!
Great experiments, I always wondered the loss from opening the door. A fact that may be interesting : all food does not warm up at the same rate, and by a lot as my experience seems to have shown. I once had a full of food chest freezer (300liters) shut down for one week (in a basement, that might be at 10°C). When I came back (7 days had passed), the vegetables and pastry were melted, but the meat was still frozen (hard as rock), and I actually saved it thanks to the advice of a vet. Also, I often unfreeze meat from the freezer in the fridge, and it can take more than one day to unfreeze. Also, my owner manual says that in these conditions, my chest freezer might stay below freezing for 3 days.
Great video! I have about 20 freezers chest and upright. This video is spot on. Keep them full and they draw less power and they will hold much better when then power goes out. A mostly empty freezer will definitely spoil first.
I've often thought about doing this exact experiment. Thank you for saving me the time.. Very interesting. I was surprised that you didn't take the opportunity to make a point of how much it cost everytime someone opened your freezer door.
Well, if it costs about six minutes of run time to open the door, and the freezer uses about 200W when running, then it's about 20Wh per open. Average cost per kWh varies, but in the USA it's about $0.13/kWh, so you're looking at around a quarter of one cent.
@@matthiasrandomstuff2221 This scientific video is instructive to the prepper morons who think that keeping their freezer full of foodstuffs and ice will keep the contents safe for many days on end. The freezer requires constant electrical power to function properly. That is, to keep food safe and edible. The freezer’s electrical needs are no different than that of an air conditioner. *Canada!* 🇨🇦 🇬🇧 🇦🇺 🇳🇿
I live in Florida, U.S. and we get plenty of lead time on hurricanes. I put 4 one gallon jugs of water along with as many disposable water bottles as possible in the freezer a couple days before a hurricane hit us. When the power went out, i took two of those gallon jugs and put them in the fridge (side-by-side fridge/freezer). We lost power for a full 3 days and we continued to use the fridge/freezer normally. Every 24 hours or so i'd rotate those gallon jugs back into the freezer and they'd re-freeze from the thermal mass in the freezer. I didn't have any thermometers in there, but nothing in the freezer thawed, and there was no discernible difference in the fridge's temp
I did similar with the winter windshield wash type antifreeze 1gal jugs when living off grid with much success. In the winter, you could just stick them in the snow as well.
You wouldn't have been able to refreeze the jugs without the freezer running. I know about this trick, all your doing it turning the fridge into a ice box. Same with the freezer it's just a ice box at that point and everyone knows you can't put something in a cooler full of ice and have it freeze. If you salt the ice maybe but then your ice is gone faster. Im sure it kept stuff pretty frozen but I know it didn't refreeze a jug of water with no power.
@@alec4672 You KNOW it didn't? I mean... why on earth would i make that up? As previously stated, i jam-packed that fridge with water bottles, you know, the disposable ones, plus the 4 gallon jugs. Let's exaggerate to drive the point home. Say the freezer temp was set to absolute zero (-459 F, -273 C). It's an Energy Star freezer (part of which means it's well insulated). Might you be able to believe that with such a cold temp it would be able to re-freeze the gallon jugs? Also, salt is irrelevant to the actual temperature of the ice. Ice doesn't stop getting cold at 32 F (0 C). Freezers usually come preset from the factory to 0 F ( -18 C ) as this is the temperature recommended by the FDA www.fda.gov/consumers/consumer-updates/are-you-storing-food-safely I just went and checked my freezer, it's set to the coldest possible setting, whatever that is, but it's got a mark at the midway point which i would guess is 0 F (-18 C), so i'm presuming it's colder than that. Lastly, when i'd swap out the milk jugs, the ones in the fridge weren't room temperature, in fact, they were still mostly ice, which would mean that the water that had melted couldn't have been much above 32 F (0 C), therefore it wasn't like they had far to go to re-freeze. If i had one of those fridge/freezers where the freezer is on the top or bottom, i don't know that the freezer would have been big enough to contain all that water i jammed into every square inch i possibly could, i.e. big enough to hold enough thermal mass. And... just to drive the point home, I'm not talking about a hypothetical here, as in, "what would i do IF..." . I'm sharing an experience i ACTUALLY had. In fact, afterwards i shared it with all my neighbors (those who don't own generators) because of course their food didn't fare too well. And, down here in Florida, when a hurricane's on its way, one of the things that disappears off every shelf in every grocery store, convenience store, pharmacy, anywhere, everywhere is water. ALL of it, including flavored water, anything close to water. So everyone's already got what they need to keep their food safe.
I keep several frozen 2 liter bottles in the freezer only taking them out to add in more food. I keep several spares next to the freezer ready as space becomes available. We live on an island, and have upwards of 10 power outages a year, most lasting several hours, but a few lasting almost a day or longer. I wish I had your know how and test equipment. I did however purchase an infrared temperature sensor you discussed in an earlier video on insulation. Thanks for yet another interesting video! My best to you and your family!
I run old excel. It works because it doesn't have to update every five minutes. Also the files are on my machine, not the "cloud". I run loads of old software, because it works. All software now is rentware in constant beta. Imagine 25 years ago, software worked on release. 1 or 2 patches over the lifetime of it.
I didn't know that was a typo until I looked it up. I thought "obolete" was a polite way of saying stupid and outdated. I'm trying to change to metric units in the shop myself and it ain't easy on a day to day basis. But starting a new project is workable.
@@matthiasrandomstuff2221 didn't mean that in a disrespectful way. And, better that it was someone like me that appreciates all of your work rather than one of the douches that dislike the video but never seems to leave any constructive reason as to why. Thanks for putting the hours in for a concise video experiment.
I drove 2600 km from France to Croatia once with some very stinky cheese in an improvised polystyrene cooler 5cm thick. , with a few frozen water bottles. I was very surprised to find water still frozen after 24 hours. It was the peak of summer.
@@matthiasrandomstuff2221 I'm almost positive our fridge has additional heating on the sides to prevent it from getting too cold, attracting humidity. Probably a bad idea indeed.
I have two freezers - both chest style. I know chest is better than upright, but not by how much. Because it's certainly true that it can be a pain in the neck getting stuff out of the bottom. I wonder if upright freezers need to be defrosted more often, since it seems that you get more unconditioned air introduced regularly.
This one works like a fridge in that it blows air. So it auto defrosts. That's good and bad. Bad for the contents (more freezer burn), good cause less hassle.
@@matthiasrandomstuff2221 Defrosting is always worse mentally than in reality. Empty the freezer, put in a fan, and it's done in little more than 15 minutes. but it's still a dreaded chore for some reason... :-D
Sounds about right. We had a power outage lasting almost exactly 24 hours during which I made sure no one opened the freezer. It was full (an upright model) and the food was fine and still frozen when the power was restored.
"Have you ever wondered how long stuff will stay frozen in your freezer if the power goes out?" Literally yesterday and now this is in my recommendations.
Very useful info for us living in a rural area with frequent power outages. It confirms the URBAN LEGEND of 36hrs w/o opening the door. Question: Do you believe that your experiment applies to horizontal freezer ? Cold air release is less when opening the door but that did not influence the duration for the vertical version significantly I believe.
The heat energy required to state-change the frozen items to liquid is very significant. So if you perform the experiment with disposable food (or bottles of water or whatever) you will find that it gets to about 0C in line with your math, but then it will just stay there for a very long time as all the additional heat energy entering the system works toward the state change.
@@matthiasrandomstuff2221 Up until buying a new freezer I had this view. They have certainly come a long way to optimise the capacity of the new drawers.
@@matthiasrandomstuff2221 the drawers are made of plastic and they take up less than 1cm on each side. And since everything in this country has a din norm they are all the same size. Frozen goods fit perfect in them, otherwise people wouldn't buy them anymore. A whole turkey wouldn't fit, but we don't have thanksgiving. Erntedank yes is pretty similar, but no turkey.
Possibly to keep kids from climbing in..? I'm guessing cost savings. In addition to the better reach, it would be nice to keep things isolated in case of an outage where spoils and leaks out onto other things.
Not seen a freezer with bare shelves in years. Went freezer shopping earlier this year and they all have pull out drawers, even my old one had drawers.
I'm not sure what's better. Drawers are very handy, but they also take up quite a bit of space themselves, so cuts down on freezer capacity. But they sure cut down on how much cold air falls out when you open it.
@@matthiasrandomstuff2221 I do think drawers make stuff inside your freezer easier to reach, especially if you've got smaller items in there. Without a drawer, you basically have a box of say 600 x 800 x 300 mm (width, depth, height), with the opening on the 600x300 side. With a drawer, your box may be slightly smaller, but you're accessing it from the 800x600 side instead of the 600x300 side. It can also help you fill your freezer to a higher degree, since you can fill a drawer to the absolute brim without worrying about something falling out, which can be an issue without drawers.
@@timderks5960 problem is with drawers you need to open the door fully to pull them out. in some house with cramped space between appliance its a pain.
i experienced this last May 2018 when there was a huge windstorm, and there was power outage for 2+ days in our area. it took 1.5 days for the stuff inside to become soft from melting.
Thanks. We had power blackouts here in Perth(Australia) over Christmas last year, and I'd like to be prepared in case Santa brings the same 'gift' again.
I administered a laboratory appliance monitoring system years ago. We had a huge outage due to a hurricane and I wasn't allowed to go back to recover the system in time so we lost some data. I did some tests with empty vs full freezers and discovered that our freezers did not last long with no power. The empty freezer at -20F would be above freezing within hours. Mass was the most important thing to add to keep the temperature below freezing so we started adding water bottles and bricks when a freezer wasn't completely full. That made a huge difference. Another issue we had was the research samples were stored in cardboard boxes so there was very little mass in normal times. We also couldn't use frost free units and any switches had to be outside the units since there were explosion risks.
Adding thermal mass [like water] to keep the food cold longer in the event of a power outage. A brilliant suggestion for those of us who don't have full freezers
Hi. I just stumbled upon this as I am doing similar experiments with my new Frigidaire freezer. One thing I wonder about is how you pass the temp sensor wire through the door seal? I have tried a number of units and their wires all causes noticeable leaks with cold air clearly exiting and frost forming inside at the point of their passage. I finally used some uxcell Flexible Flat Cable with some 3.5mm phone plugs to "splice" between the sensor and the thermometer head unit. This seems to address the issue. But it causes wild temperature fluctuations when charging the head unit. So I am still looking for a better solution. Thanks!
That's a pretty cool experiment. Perhaps you could fabricate an internal cold air dam door for the bottom 1/2 or 2/3 of the freezer to hold the cold air in when the door is opened? A compromise between chest freezer power efficiency and upright freezer space use efficiency & convenience.
They have their drawbacks though. For that sweet efficiency and lower "cold" losses you're giving up ease of access / order . And chest-type would need to be de-iced periodically, while vertical ones are usually automatic or no-ice buildup at all. Technology Connections did a video on chest-type freezers :)
@@eDoc2020 I second this. I would be interested to see a direct comparison with just tilting this vertical freezer on its back and doing the door open test. I suppose if you had a chest freezer you could do the same by standing it on end and measuring the difference.
@@BravoCharleses Don't do that. Refrigeration systems (at least this style) only work if they're properly oriented. The manuals for refrigerators and air conditioners will usually say to wait 24 hours before powerup if it's been on its side because this can cause damage.
People who use a bulk freezer (usually a chest freezer in the garage), as they used up to contents, they would put bags of grass to fill up the space, supposed to make the freezer more efficient due to thermal mass, and for the same reason if there was a power cut it would take longer to thaw out. People with a bulk freezer would usually have a 'day freezer' in the house.
The graph at 1:55 isn't quite accurate for a freezer with a bunch of stuff in it. The temp won't change much (if at all) as things go through the state change of being a solid to a liquid. So the slope will change (flatten as the heat energy goes into doing the state change and not moving the temp) as it nears 0 degrees and stuff starts thawing.
I wonder how a comparable top opening freezer compares with opening/closing. Technology Connections has a good video on deep freezes, pointing out that they’re so efficient because of the door design. Much less convenient when you need to find something, though.
At 4:11, are they power tool batteries in the door shelf? Is there a reason for that, if so I would like to see a video if you have not done one already.
Informative Matthias. Wonder what difference it would make if you added foam board insulation over the body of the fridge (except the heat exchanger ofcourse). I imagine you can use packing tape to stick the foam board rather than gluing it to the fridge!
@@AppalachianLife Technology Connections did a video about chest freezers: ruclips.net/video/CGAhWgkKlHI/видео.html Basically, chest freezers can be super efficient bc the top lid prevents cold air from spilling out which also minimizes warm moist air from going in. So auto defrost is not really necessary.
@@JonnyDIY If you keep the freezer temperature relatively constant the compressor will need to sustain a specific duty cycle over time. In other words, it will run for the same number of hours each day. If it's unpowered when it would otherwise have run for three hours, it will run for those three hours when you plug it back in.
@@eDoc2020 ohh ok I see. I was just thinking you could cycle it on and off but I guess it does that already with the thermostat. Was trying to find a way to save electricity for chest freezer off the grid
I would be interested to find out the effects of where the freezer was placed. Unconditioned garage vs Conditioned basement. Are you able to calculate the effective insulation value for the freezer and the surface area?
A possible experiment if you want to do a follow up to find ways to improve those numbers. Bottles of salt water in the freezer. Salt helps a lot with lowering the freezing point of water, I use the stuff in my cooler to make 4lbs of ice last a couple of days in the middle of summer.
We lost power for 53 hours and everything stayed frozen. It was very full and also an expensive one, so maybe a bit higher quality than most. We were worried, because it was just before Christmas and we had a lot of frozen food for Christmas dinner.
Add plexiglass panels to divide the opening into 3 parts, also fill the empty space with lightweight bricks to increase thermal mass. And retest, loose the food, consider bricks to be food replacment. In reality-based use you would fill with thermal mass and swap in food.
Nice, i enjoyed watching this, would watch something similar in future. I didnt even think of how a cooling device doesnt stay at a constant temperature. So would it be more efficient to open them at the end of a duty cycle or right before one, or?
A couple of mechanical engineers here did build a solar powered fridge, but instead of electrochemical batteries they used water to make salty-ice. They achieved a considerable lower maintenance cost, since batteries would have to be replaced every few years.
Special thanks for translating to obsolete units for those of us down here in "We're Number One" land. However, I'm surprised you're using "our" stupid date format (medium unit / small unit / large unit). Is that common in Canada?
Matthias, do you think a DC inverter refrigerator would be more economical since the compressor can operate a various speeds? It seems to be the case with the HVAC split units I've seen. Maybe slow and steady is more economical than ON or OFF.
Should you not subtract around 12 minutes from the 26 hours if the power is off as it was 6 minutes run time for the compressor but the compressor is only on roughly half the time with power on?
I was a food hoarder of sorts. A man and his wife had two full chest freezers and two full freezer compartments in two refrigerator/freezers. We had a power failure and I panicked. There was a lot of meat in the freezers. I spent over $200 on dry ice at the grocery to maintain the freezers. Nothing thawed out. For everyones information, none of the dry ice lasted more than 24 hours in either chest type freezer and the lids were never opened. I got two loads of ice but don't remember how many pounds that was but it was not much I assure you.
Hi Matthias, I got me one of those HS110 units - and tried to read its output from anything except the App it comes with ... hm, it is not so easy! You mention 'reading from python' - do you by any chance have some notes on that which we could read up on?
You could use this information to calculate the Wh cost of opening the door. It could also be interesting to find out what the relationship between increased energy consumption and length of time the door is open is.
This is why e.g. Liebherr Freezers (and others, of course) have drawers, so that no significant air exchange takes place despite the freezer being opened.
@@seigeengine usually freezers with drawers are more modern and therefore are more energy efficient and better insulated but you can get a cheapoorly insulated with drawers or the other way around in Europe it is mandatory to show the efficiency and average power consumption which is measured by a standardized process (like WLTP for cars) so you just need to look for that to have at least a relative comparison
Recently had a power outage and did some research to see how long my food will last. US gov recommends food is safe in the fridge up to 4 hours from losing power. From my memory fridge temp is around 40 degrees. So going off Matthias’s numbers you have 36 hours to melting point + unknown time from melting point to fridge temp of 40 degrees + 4 hours above 40 degrees. So that 36 hours is at least 4 hours longer.
If you are going to consume the food coming out of the freezer, you can go much longer. But the food you won't consume will have thawed and if you don't eat it, it's kind of spoiled.
So as someone who likes to browse my fridge/freezer constantly for something to eat, how much does it cost (in increased power usage from the changing duty cycle) each time I open the door?
I also have an upright freezer. Our fridge/freezer doesnt have an ice maker. So I just use an ice cream bucket and fill it with ice from a small stand alone ice maker I have. Worst idea I had to use the stan up freezer to store the ice cubes. 1) it was a super huge waste of efficiency on the freezer to keep opening the door to get ice like 10x a day. 2) this freezer needs occasional defrosting bout every 10 months. Well with using it to hold ice and opening the door 10x a day the frost was built up in about 3 months. Changed back to the fridge/freezer unit.
I live these experiments! What do you think of a comparison of opening a fridge twice (to take an item out and put it back) or to leave it open for 10 seconds (while getting a pickle out of a jar, for example)?
Exactly my thoughts too, I just commented that. There needs to be a balance someone in the middle. The act of opening the door already replaces all of the cold air, it's just so inefficient.
The tp link energy monitoring smart switches are now hard to get and very expensive, the site says they are at end of life. What to use now? I want to monitor my new hybrid water heater and my sense won’t detect it and I know no other way to get it into Sense.
Hm, only lived in Germany, Netherlands, Qatar and Oman I never experienced a power cut lasting longer than 30 minutes. Maybe there is a reason why a lot of countries have put their power lines underground instead of keeping those ridiculous troublesome overland power lines? Looks like the old style chest design freezers do have their advantages.
In January 1980 we had almost 2 weeks of outage, b/c ice rain built up lots of ice on the overland power grid backbone wires, and some alleged RAF ("Rote Armee Fraktion" - german leftist terrorists, not Royal Air Force) sabotage on the space frame masts from years earlier plus corrosion at this areas made some power grid backbone masts collapse. That was only 55km out of Munich.
Upright freezer. I'd love to see this done with a deep freezer with their much more efficient design. Cold air sinks so it takes on much less heat when open the door.
Nice one Matthias. Here's a thought... If you're freezing a litre of water, is it more efficient to cool it in the fridge first and then freeze it, or just go the freezer route from scratch?
So I’m guessing 1 minute of the freezer being open would loose approximately would be 1.3 hours of a reduction in freezing temperature that leaked out based on the calculations.
Like me, you might find yourself with a Freezer whose controller circuits crap-out..mostly because they don't put zero-crossing relays on their controller boards. I replaced the entire controller board with an SBC (AT-Tiny) and sensors and wound up with a FAR more efficient freezer than the manufacturer gave me.
Wouldn't the freezer stay at 0C for a significant amount of time while the phase change from frozen to thawed/molten food happens? Like how a glass of water with ice will stay cold until the ice has completely melted.
I wonder how the temperature of the actual food changes as compared to the air temperature in the freezer. I would suspect you would have a few hours from when the air temperature passes the melting point to when the food actually melts. You could put a temperature probe in a block of ice to simulate this.
The air gets the temperature from the food. Outside insulation is quite good, so measuring the air temperature is representative of the average for the food.
@@matthiasrandomstuff2221 That makes sense. I suppose then you could use frozen salt water (or something with a lower freezing point) to buffer the temperature if you are expecting an outage. It just needs to be something with a freezing point between the freezer temperature and the melting point of the food.
I love your random experiments. Very thorough and entertaining.,
Amen brother
Or sister🤷
Random? This is very useful information.
I repair powerlines for a major utility, people always stop me(while I'm in the process of restoring power mind you) and ask how long it'll take because they don't want their food to go bad.
I understand their concerns. I also like having my power on.
So I can't wait to send them here.
I'm sorry you have to do your job out in the open. I was in IT, and we would hide in the server room so we could fix things with fewer questions.
I really appreciate you linemen! We have many outages a year (usually due to weather and falling trees). You folks get on the job very quickly no matter how bad the weather. For that I am grateful! Cheers!
Quick story.
We were working a storm a few years back. We we're on our 8th day of 18 hr days(yeah, it's doubled bubble), this little tiny old lady pulls up while I'm booming down to get more supplies. So I hear this encounter.
She wants to know when the power is coming back. She has meat in the freezer and is concerned. If she was anything like my own grandmother it was probably a single hamburger, slices from a left over ham, and one individually wrapped hotdogs. The groundman tells her a few hours to most 10 hours. It was an ice storm... an act of God... anyway we felt bad for her but there was 8 hrs of work... so she starts yelling at us. Now, she probably never did a day of hard work and she's yelling at guys that have been working 18hrs a day for about 8 days straight, climbing pole covered in ice and stuff, right... which is fine. Seriously none of us mind getting yelled at by lunatics. It's part of the job.
So when she goes to drive off she yells
"My meats gonna go bad" as if we were directly to blame and not helping the situation.
My co-worker says as a matter of fact but not so she could hear "Lady, your meat went bad a long time ago."
Funniest thing ever. I laughed for the rest of the day. I still drive around and remember it and laugh.
Whenever my wife is concerned about leftovers not getting eaten I'll say "lady, you're meat..."
"Enough! Not again. Just eat the food"
So that's my story.
@@richardpatterson4312 hah! Love it!
I am getting proper wiring out to my shed soon and I was worried about how long the frozen stuff would last before it warmed up too much. Your psychic abilities are definitely improving!
Great experiments, I always wondered the loss from opening the door.
A fact that may be interesting : all food does not warm up at the same rate, and by a lot as my experience seems to have shown.
I once had a full of food chest freezer (300liters) shut down for one week (in a basement, that might be at 10°C). When I came back (7 days had passed), the vegetables and pastry were melted, but the meat was still frozen (hard as rock), and I actually saved it thanks to the advice of a vet.
Also, I often unfreeze meat from the freezer in the fridge, and it can take more than one day to unfreeze.
Also, my owner manual says that in these conditions, my chest freezer might stay below freezing for 3 days.
Sounds like you're talking about very large pieces of meat.
Great video! I have about 20 freezers chest and upright. This video is spot on. Keep them full and they draw less power and they will hold much better when then power goes out. A mostly empty freezer will definitely spoil first.
I use the ICE PACK things to fill empty space in the freezer and water jugs in the icebox.
I've often thought about doing this exact experiment. Thank you for saving me the time.. Very interesting. I was surprised that you didn't take the opportunity to make a point of how much it cost everytime someone opened your freezer door.
Well, if it costs about six minutes of run time to open the door, and the freezer uses about 200W when running, then it's about 20Wh per open.
Average cost per kWh varies, but in the USA it's about $0.13/kWh, so you're looking at around a quarter of one cent.
it's 6 minutes of heat leakage. Multiply by compressor duty cycle, of about 40%, times power consumption of about 80 watts.
@@matthiasrandomstuff2221 This scientific video is instructive to the prepper morons who think that keeping their freezer full of foodstuffs and ice will keep the contents safe for many days on end.
The freezer requires constant electrical power to function properly. That is, to keep food safe and edible. The freezer’s electrical needs are no different than that of an air conditioner.
*Canada!* 🇨🇦 🇬🇧 🇦🇺 🇳🇿
I found this super interesting, thanks for doing these random research projects and sharing the results with us.
I live in Florida, U.S. and we get plenty of lead time on hurricanes. I put 4 one gallon jugs of water along with as many disposable water bottles as possible in the freezer a couple days before a hurricane hit us. When the power went out, i took two of those gallon jugs and put them in the fridge (side-by-side fridge/freezer). We lost power for a full 3 days and we continued to use the fridge/freezer normally. Every 24 hours or so i'd rotate those gallon jugs back into the freezer and they'd re-freeze from the thermal mass in the freezer. I didn't have any thermometers in there, but nothing in the freezer thawed, and there was no discernible difference in the fridge's temp
I did similar with the winter windshield wash type antifreeze 1gal jugs when living off grid with much success. In the winter, you could just stick them in the snow as well.
@@Jaspel hey, dont come bragging about your fancy snow to us Floridians, we dont know what it is
wow that's amazing it could keep refreezing for so long
You wouldn't have been able to refreeze the jugs without the freezer running. I know about this trick, all your doing it turning the fridge into a ice box. Same with the freezer it's just a ice box at that point and everyone knows you can't put something in a cooler full of ice and have it freeze. If you salt the ice maybe but then your ice is gone faster. Im sure it kept stuff pretty frozen but I know it didn't refreeze a jug of water with no power.
@@alec4672 You KNOW it didn't? I mean... why on earth would i make that up? As previously stated, i jam-packed that fridge with water bottles, you know, the disposable ones, plus the 4 gallon jugs.
Let's exaggerate to drive the point home. Say the freezer temp was set to absolute zero (-459 F, -273 C). It's an Energy Star freezer (part of which means it's well insulated). Might you be able to believe that with such a cold temp it would be able to re-freeze the gallon jugs?
Also, salt is irrelevant to the actual temperature of the ice. Ice doesn't stop getting cold at 32 F (0 C).
Freezers usually come preset from the factory to 0 F ( -18 C ) as this is the temperature recommended by the FDA www.fda.gov/consumers/consumer-updates/are-you-storing-food-safely
I just went and checked my freezer, it's set to the coldest possible setting, whatever that is, but it's got a mark at the midway point which i would guess is 0 F (-18 C), so i'm presuming it's colder than that.
Lastly, when i'd swap out the milk jugs, the ones in the fridge weren't room temperature, in fact, they were still mostly ice, which would mean that the water that had melted couldn't have been much above 32 F (0 C), therefore it wasn't like they had far to go to re-freeze.
If i had one of those fridge/freezers where the freezer is on the top or bottom, i don't know that the freezer would have been big enough to contain all that water i jammed into every square inch i possibly could, i.e. big enough to hold enough thermal mass.
And... just to drive the point home, I'm not talking about a hypothetical here, as in, "what would i do IF..." . I'm sharing an experience i ACTUALLY had. In fact, afterwards i shared it with all my neighbors (those who don't own generators) because of course their food didn't fare too well. And, down here in Florida, when a hurricane's on its way, one of the things that disappears off every shelf in every grocery store, convenience store, pharmacy, anywhere, everywhere is water. ALL of it, including flavored water, anything close to water. So everyone's already got what they need to keep their food safe.
Awesome information and data sir! A video between you and ProjectFarm would be incredibly mind blowing 🤯
Matthias is asking all the questions we needed answered
I keep several frozen 2 liter bottles in the freezer only taking them out to add in more food. I keep several spares next to the freezer ready as space becomes available. We live on an island, and have upwards of 10 power outages a year, most lasting several hours, but a few lasting almost a day or longer. I wish I had your know how and test equipment. I did however purchase an infrared temperature sensor you discussed in an earlier video on insulation. Thanks for yet another interesting video! My best to you and your family!
Put 50/50 water and antifreeze in the bottles. That way they thaw before the food will, and give off even more cold in the process.
That version of Excel is older than some of the viewers probably
right
about 21 years. Super snappy on a modern computer!
@@matthiasrandomstuff2221 At least, you didn't use visicalc. LOL
I run old excel. It works because it doesn't have to update every five minutes. Also the files are on my machine, not the "cloud". I run loads of old software, because it works. All software now is rentware in constant beta. Imagine 25 years ago, software worked on release. 1 or 2 patches over the lifetime of it.
@@matthiasrandomstuff2221 So yes. I started watching the channel probably when I was 14 or so.
Apparently the letter S is obolete as well.
Thanks for transferring to "obolete" units for us ;)
I didn't know that was a typo until I looked it up. I thought "obolete" was a polite way of saying stupid and outdated.
I'm trying to change to metric units in the shop myself and it ain't easy on a day to day basis. But starting a new project is workable.
oops, typo.
@@matthiasrandomstuff2221 didn't mean that in a disrespectful way. And, better that it was someone like me that appreciates all of your work rather than one of the douches that dislike the video but never seems to leave any constructive reason as to why. Thanks for putting the hours in for a concise video experiment.
I read obSOlete, even in your comment! Hahahaha!
Aren’t oboletes a muscle group? Obletes... bah
I drove 2600 km from France to Croatia once with some very stinky cheese in an improvised polystyrene cooler 5cm thick. , with a few frozen water bottles. I was very surprised to find water still frozen after 24 hours. It was the peak of summer.
Thawing a water bottle takes the same as heating it from 0-80 degrees. So those wtater bottles can take up a huge amount of heat to keep things cool.
@@matthiasrandomstuff2221 I'll take your word for it. I'm a practical guy that doesn't delve too deeply into the science of things.
And pray tell what stinky but great tasting delicious treat did you bring to France the other way from Croatia?
@@Don.Challenger rakija
@@matthiasrandomstuff2221 you meant "0-80 degrees" to be interpreted as 0 °C (32°F - frozen water) to 80 °F (car temperature), right?
I wonder if a change in ambient temperature would make a difference to the results. For example a freezer in the UK in the winter. Great video 👍🏼
I think RH has a big factor as well.
Yes, heat loss through conduction is U*A*dT (resistance to heat flow * area * temperature differential).
In northern Alaska a freezer outside in winter takes no energy. Did I say freezer? I meant snow bank. Yes, ambient temperature matters.
Would the freezer be much better if you added more insulation on the outside? Does the manufacturer cheap out on insulation?
Absolutely not. The outisde coils are just against the walls. If you put insulation on them, it can't shed heat anymore, and it will overheat.
@@matthiasrandomstuff2221 I'm almost positive our fridge has additional heating on the sides to prevent it from getting too cold, attracting humidity.
Probably a bad idea indeed.
Love it! I wonder how the chest type freezer would be effected as the air will not flow to the bottom
Excellent video. Thank you. Great info to know as an off gridder
I have two freezers - both chest style. I know chest is better than upright, but not by how much. Because it's certainly true that it can be a pain in the neck getting stuff out of the bottom. I wonder if upright freezers need to be defrosted more often, since it seems that you get more unconditioned air introduced regularly.
This one works like a fridge in that it blows air. So it auto defrosts. That's good and bad. Bad for the contents (more freezer burn), good cause less hassle.
@@matthiasrandomstuff2221 Defrosting is always worse mentally than in reality. Empty the freezer, put in a fan, and it's done in little more than 15 minutes. but it's still a dreaded chore for some reason... :-D
@@Wordsnwood also break 3inch+ of ice with a kitchen knife.
Sounds about right. We had a power outage lasting almost exactly 24 hours during which I made sure no one opened the freezer. It was full (an upright model) and the food was fine and still frozen when the power was restored.
i love those little informative test.
i be curious to see your stand up vs a chest cooler
"Have you ever wondered how long stuff will stay frozen in your freezer if the power goes out?" Literally yesterday and now this is in my recommendations.
Very useful info for us living in a rural area with frequent power outages. It confirms the URBAN LEGEND of 36hrs w/o opening the door. Question: Do you believe that your experiment applies to horizontal freezer ? Cold air release is less when opening the door but that did not influence the duration for the vertical version significantly I believe.
The heat energy required to state-change the frozen items to liquid is very significant. So if you perform the experiment with disposable food (or bottles of water or whatever) you will find that it gets to about 0C in line with your math, but then it will just stay there for a very long time as all the additional heat energy entering the system works toward the state change.
really nice, would love a comparison to a chest style freezer, they use them on boats all the time.
I think there is a reason why all the upright freezers in Europe have drawers.
I thought of the same thing when i watched this video... cant speak for all of Europe but for Scandinavia atleast 😀
Drawers are nice, but drawers themsleves take up a lot of space too, so I have mixed feelings on that.
@@matthiasrandomstuff2221 Up until buying a new freezer I had this view. They have certainly come a long way to optimise the capacity of the new drawers.
@@matthiasrandomstuff2221 the drawers are made of plastic and they take up less than 1cm on each side. And since everything in this country has a din norm they are all the same size. Frozen goods fit perfect in them, otherwise people wouldn't buy them anymore. A whole turkey wouldn't fit, but we don't have thanksgiving. Erntedank yes is pretty similar, but no turkey.
Possibly to keep kids from climbing in..? I'm guessing cost savings.
In addition to the better reach, it would be nice to keep things isolated in case of an outage where spoils and leaks out onto other things.
I did not need to learn about your fridge and yet I'll be dawned if I ever don't enjoy one of your videos:))
Thanks for the video Matthias, your data will come in handy this hurricane season!
Not seen a freezer with bare shelves in years. Went freezer shopping earlier this year and they all have pull out drawers, even my old one had drawers.
I'm not sure what's better. Drawers are very handy, but they also take up quite a bit of space themselves, so cuts down on freezer capacity. But they sure cut down on how much cold air falls out when you open it.
@@matthiasrandomstuff2221 I do think drawers make stuff inside your freezer easier to reach, especially if you've got smaller items in there. Without a drawer, you basically have a box of say 600 x 800 x 300 mm (width, depth, height), with the opening on the 600x300 side. With a drawer, your box may be slightly smaller, but you're accessing it from the 800x600 side instead of the 600x300 side. It can also help you fill your freezer to a higher degree, since you can fill a drawer to the absolute brim without worrying about something falling out, which can be an issue without drawers.
@@timderks5960 problem is with drawers you need to open the door fully to pull them out. in some house with cramped space between appliance its a pain.
@@Francois_Dupont That's true, but that's an extremely specific issue.
i experienced this last May 2018 when there was a huge windstorm, and there was power outage for 2+ days in our area. it took 1.5 days for the stuff inside to become soft from melting.
36 hours like I said!
Would a chest freezer last longer.?
@@nkg6013 all else being the same, yes
@@jasonharrison25 that's what we always had growing up in rural middle of nowhere!
Chest keeps the cold in better, but you need to organise the layout or you have more open time to dig down and grab things.
Thanks. We had power blackouts here in Perth(Australia) over Christmas last year, and I'd like to be prepared in case Santa brings the same 'gift' again.
I administered a laboratory appliance monitoring system years ago. We had a huge outage due to a hurricane and I wasn't allowed to go back to recover the system in time so we lost some data. I did some tests with empty vs full freezers and discovered that our freezers did not last long with no power. The empty freezer at -20F would be above freezing within hours.
Mass was the most important thing to add to keep the temperature below freezing so we started adding water bottles and bricks when a freezer wasn't completely full. That made a huge difference.
Another issue we had was the research samples were stored in cardboard boxes so there was very little mass in normal times. We also couldn't use frost free units and any switches had to be outside the units since there were explosion risks.
Water holds WAY more heat per mass than bricks.
Adding thermal mass [like water] to keep the food cold longer in the event of a power outage. A brilliant suggestion for those of us who don't have full freezers
I have no idea why this information enriches my life, but it definitely does
Is no one going to ask about the frozen batteries at 4:08!? Are they just chilling?
Lithium batteries do btter in the cold - or run a pait i wires outside the freezer to a set of batteries
Hi. I just stumbled upon this as I am doing similar experiments with my new Frigidaire freezer. One thing I wonder about is how you pass the temp sensor wire through the door seal? I have tried a number of units and their wires all causes noticeable leaks with cold air clearly exiting and frost forming inside at the point of their passage. I finally used some uxcell Flexible Flat Cable with some 3.5mm phone plugs to "splice" between the sensor and the thermometer head unit. This seems to address the issue. But it causes wild temperature fluctuations when charging the head unit. So I am still looking for a better solution. Thanks!
That's a pretty cool experiment. Perhaps you could fabricate an internal cold air dam door for the bottom 1/2 or 2/3 of the freezer to hold the cold air in when the door is opened? A compromise between chest freezer power efficiency and upright freezer space use efficiency & convenience.
Lol, this video is perfectly timed. Came to work today, and three lab freezers were room temperature and I had to throw out a lot of samples.
Nice haircut, good job Rachel. 🙂
Is John Heisz stuffed away in that freezer?
Conclusion: purchase a chest-type freezer instead.
for pure efficiency, yes
They have their drawbacks though.
For that sweet efficiency and lower "cold" losses you're giving up ease of access / order .
And chest-type would need to be de-iced periodically, while vertical ones are usually automatic or no-ice buildup at all.
Technology Connections did a video on chest-type freezers :)
For a chest freezer, better to fill the bottom with gallon jugs of water. No one digs to the bottom.
The drawing besides the fridge is of Les Portes Saint Louis is Old Quebec City.
I love everything about this. Such a great and smart way to think about something.
Not that I think you'd learn anything from it, but have you seen the Technology connections video on chest freezers?
It would be nice if somebody did the same tests Matthias did here but with a chest freezer. I wonder how much of a benefit a chest freezer would have.
@@eDoc2020 I second this. I would be interested to see a direct comparison with just tilting this vertical freezer on its back and doing the door open test. I suppose if you had a chest freezer you could do the same by standing it on end and measuring the difference.
@@BravoCharleses Don't do that. Refrigeration systems (at least this style) only work if they're properly oriented. The manuals for refrigerators and air conditioners will usually say to wait 24 hours before powerup if it's been on its side because this can cause damage.
Ahh - that’s the benefit of a chest freezer (maybe?)
It’d be interesting to contrast the two.
Most interesting information!
People who use a bulk freezer (usually a chest freezer in the garage), as they used up to contents, they would put bags of grass to fill up the space, supposed to make the freezer more efficient due to thermal mass, and for the same reason if there was a power cut it would take longer to thaw out.
People with a bulk freezer would usually have a 'day freezer' in the house.
I've always wondered if keeping the fridge open vs opening and closing twice/3 lets more hot air in. I wonder if it could be tested.
could be tested, but by someone else. I have satisfied my curiosity.
The graph at 1:55 isn't quite accurate for a freezer with a bunch of stuff in it. The temp won't change much (if at all) as things go through the state change of being a solid to a liquid. So the slope will change (flatten as the heat energy goes into doing the state change and not moving the temp) as it nears 0 degrees and stuff starts thawing.
I wonder how a comparable top opening freezer compares with opening/closing. Technology Connections has a good video on deep freezes, pointing out that they’re so efficient because of the door design. Much less convenient when you need to find something, though.
At 4:11, are they power tool batteries in the door shelf? Is there a reason for that, if so I would like to see a video if you have not done one already.
Informative Matthias. Wonder what difference it would make if you added foam board insulation over the body of the fridge (except the heat exchanger ofcourse). I imagine you can use packing tape to stick the foam board rather than gluing it to the fridge!
I'd love to see this on a chest freezer as well.
I don't have one.
most chest freezers are not auto defrost, no thanks.
@@matthiasrandomstuff2221 Ordered one of those meters and will share data when I get a roundtoit.
@@AppalachianLife Technology Connections did a video about chest freezers: ruclips.net/video/CGAhWgkKlHI/видео.html
Basically, chest freezers can be super efficient bc the top lid prevents cold air from spilling out which also minimizes warm moist air from going in. So auto defrost is not really necessary.
@@AppalachianLife It's better without auto defrost, since that's what causes freezer burn.
Did you end up putting a timer on the power to cycle the freezer on/off for x amount of hours? 🤔
that would be stupid.
@@matthiasrandomstuff2221 ohh, I thought it would save power. Thank you for the nice response 😂🤙
@@JonnyDIY If you keep the freezer temperature relatively constant the compressor will need to sustain a specific duty cycle over time. In other words, it will run for the same number of hours each day. If it's unpowered when it would otherwise have run for three hours, it will run for those three hours when you plug it back in.
@@eDoc2020 ohh ok I see. I was just thinking you could cycle it on and off but I guess it does that already with the thermostat. Was trying to find a way to save electricity for chest freezer off the grid
I would be interested to find out the effects of where the freezer was placed. Unconditioned garage vs Conditioned basement. Are you able to calculate the effective insulation value for the freezer and the surface area?
A possible experiment if you want to do a follow up to find ways to improve those numbers. Bottles of salt water in the freezer. Salt helps a lot with lowering the freezing point of water, I use the stuff in my cooler to make 4lbs of ice last a couple of days in the middle of summer.
If you still have that water heater insulating blanket, Id be curious how it might affect the outcome. What was the insulating value of this freezer?
4:11 are those dewalt batteries in there??
We lost power for 53 hours and everything stayed frozen. It was very full and also an expensive one, so maybe a bit higher quality than most. We were worried, because it was just before Christmas and we had a lot of frozen food for Christmas dinner.
Add plexiglass panels to divide the opening into 3 parts, also fill the empty space with lightweight bricks to increase thermal mass. And retest, loose the food, consider bricks to be food replacment. In reality-based use you would fill with thermal mass and swap in food.
Nice, i enjoyed watching this, would watch something similar in future. I didnt even think of how a cooling device doesnt stay at a constant temperature. So would it be more efficient to open them at the end of a duty cycle or right before one, or?
This experiment is very interesting and informative.
Me trying to get food very quitly at night:
Open door:
Fridge: Lets make some music!
Nice to see that Mathias use a smart adaptor now istead of a kill a what meter.
A couple of mechanical engineers here did build a solar powered fridge, but instead of electrochemical batteries they used water to make salty-ice. They achieved a considerable lower maintenance cost, since batteries would have to be replaced every few years.
Translating to OBOLETE units = why i love you :D
Special thanks for translating to obsolete units for those of us down here in "We're Number One" land.
However, I'm surprised you're using "our" stupid date format (medium unit / small unit / large unit). Is that common in Canada?
Matthias, do you think a DC inverter refrigerator would be more economical since the compressor can operate a various speeds? It seems to be the case with the HVAC split units I've seen. Maybe slow and steady is more economical than ON or OFF.
That would make sense. Though the small tube that the liquid has to go thru to make back pressure would also have to be adjusted too.
That's consistent with the instruction manual of my freezer that states 20 hours.
Nice. Thermal mass is REAL.
Love stuff like this..
Who else but you would think of making this experiment.. thats why i follow you. Thanks 😀
Should you not subtract around 12 minutes from the 26 hours if the power is off as it was 6 minutes run time for the compressor but the compressor is only on roughly half the time with power on?
But that same compressor on half the time must be compensated for again when calculating the time to thaw, so it cancels out.
I was a food hoarder of sorts. A man and his wife had two full chest freezers and two full freezer compartments in two refrigerator/freezers. We had a power failure and I panicked. There was a lot of meat in the freezers. I spent over $200 on dry ice at the grocery to maintain the freezers. Nothing thawed out. For everyones information, none of the dry ice lasted more than 24 hours in either chest type freezer and the lids were never opened. I got two loads of ice but don't remember how many pounds that was but it was not much I assure you.
Yes, that is always a risk. Or worse yet, somehow knocking the plug loose without noticing.
1:18 _"Translating to obsolete units"_
roflmao
not disagreeing, just amused.
So when I lose power it’s best to open the fridge when the compressor is on?
Hi Matthias, I got me one of those HS110 units - and tried to read its output from anything except the App it comes with ... hm, it is not so easy! You mention 'reading from python' - do you by any chance have some notes on that which we could read up on?
You could use this information to calculate the Wh cost of opening the door.
It could also be interesting to find out what the relationship between increased energy consumption and length of time the door is open is.
why do you keep batteries in the freezer?
This is why e.g. Liebherr Freezers (and others, of course) have drawers, so that no significant air exchange takes place despite the freezer being opened.
Why were there tool batteries in the freezer?
I keep jugs of water in mine, which freeze and add to the length of time things stay cold inside in an outage.
Same experiments with Box Freezer would be interesting as a comparison.
less loss on opening the door else pretty much the same
it comes down to insulation after all
@@suit1337 I believe chest freezers are typically better insulated as well.
@@seigeengine
usually freezers with drawers are more modern and therefore are more energy efficient and better insulated
but you can get a cheapoorly insulated with drawers or the other way around
in Europe it is mandatory to show the efficiency and average power consumption which is measured by a standardized process (like WLTP for cars) so you just need to look for that to have at least a relative comparison
Recently had a power outage and did some research to see how long my food will last. US gov recommends food is safe in the fridge up to 4 hours from losing power. From my memory fridge temp is around 40 degrees. So going off Matthias’s numbers you have 36 hours to melting point + unknown time from melting point to fridge temp of 40 degrees + 4 hours above 40 degrees. So that 36 hours is at least 4 hours longer.
If you are going to consume the food coming out of the freezer, you can go much longer. But the food you won't consume will have thawed and if you don't eat it, it's kind of spoiled.
So as someone who likes to browse my fridge/freezer constantly for something to eat, how much does it cost (in increased power usage from the changing duty cycle) each time I open the door?
I also have an upright freezer. Our fridge/freezer doesnt have an ice maker. So I just use an ice cream bucket and fill it with ice from a small stand alone ice maker I have. Worst idea I had to use the stan up freezer to store the ice cubes. 1) it was a super huge waste of efficiency on the freezer to keep opening the door to get ice like 10x a day. 2) this freezer needs occasional defrosting bout every 10 months. Well with using it to hold ice and opening the door 10x a day the frost was built up in about 3 months. Changed back to the fridge/freezer unit.
I live these experiments! What do you think of a comparison of opening a fridge twice (to take an item out and put it back) or to leave it open for 10 seconds (while getting a pickle out of a jar, for example)?
Exactly my thoughts too, I just commented that. There needs to be a balance someone in the middle.
The act of opening the door already replaces all of the cold air, it's just so inefficient.
Why not add an LDR sensor to check the light goes off when the door is closed?
So how much does it cost every time you open your freezer?
Add some ice blocks to create more surface area, and to extend food preservation if power goes out.
Can you actually calculate how much it costs to open your freezer. just flat number would be cool to know.
The tp link energy monitoring smart switches are now hard to get and very expensive, the site says they are at end of life. What to use now? I want to monitor my new hybrid water heater and my sense won’t detect it and I know no other way to get it into Sense.
I only knew about -40 C = -40 F, had never considered there was a (close) symmetrical point around numeric value 0, -11.4 = 11.4 :) - History is fun
I’m convinced the only reason he included the conversion was to show off that fun little fact :)
no, I was kind of surprised at that one myself. First I thought I made a mistake when the numbers were the same.
knew*
@@aaronalquiza9680 fixed, thank you.
It will happen with any two scales which have a different zero point. For example, -136.58 degrees Celsius equals 136.58 Kelvin.
Hm, only lived in Germany, Netherlands, Qatar and Oman I never experienced a power cut lasting longer than 30 minutes. Maybe there is a reason why a lot of countries have put their power lines underground instead of keeping those ridiculous troublesome overland power lines? Looks like the old style chest design freezers do have their advantages.
In January 1980 we had almost 2 weeks of outage, b/c ice rain built up lots of ice on the overland power grid backbone wires, and some alleged RAF ("Rote Armee Fraktion" - german leftist terrorists, not Royal Air Force) sabotage on the space frame masts from years earlier plus corrosion at this areas made some power grid backbone masts collapse. That was only 55km out of Munich.
Upright freezer. I'd love to see this done with a deep freezer with their much more efficient design. Cold air sinks so it takes on much less heat when open the door.
Nice one Matthias.
Here's a thought...
If you're freezing a litre of water, is it more efficient to cool it in the fridge first and then freeze it, or just go the freezer route from scratch?
So I’m guessing 1 minute of the freezer being open would loose approximately would be 1.3 hours of a reduction in freezing temperature that leaked out based on the calculations.
no. once the cold air has fallen out the rate of coolness loss decreases
Like me, you might find yourself with a Freezer whose controller circuits crap-out..mostly because they don't put zero-crossing relays on their controller boards. I replaced the entire controller board with an SBC (AT-Tiny) and sensors and wound up with a FAR more efficient freezer than the manufacturer gave me.
I miss when freezers just had a thermostat. Much cheaper to replace.
Can you try this experiment with a chest freezer?
This is the sort of data I like. If the AI mad concentrated on useful shit rather than adverts and selling crap, the world might be a better place.
Wouldn't the freezer stay at 0C for a significant amount of time while the phase change from frozen to thawed/molten food happens? Like how a glass of water with ice will stay cold until the ice has completely melted.
Yes, it would, but by that time your food is thawing.
I wonder how the temperature of the actual food changes as compared to the air temperature in the freezer. I would suspect you would have a few hours from when the air temperature passes the melting point to when the food actually melts. You could put a temperature probe in a block of ice to simulate this.
The air gets the temperature from the food. Outside insulation is quite good, so measuring the air temperature is representative of the average for the food.
@@matthiasrandomstuff2221 That makes sense. I suppose then you could use frozen salt water (or something with a lower freezing point) to buffer the temperature if you are expecting an outage. It just needs to be something with a freezing point between the freezer temperature and the melting point of the food.