How long does a freezer stay frozen when the power goes out? • Hacker News Board

Re: How long does a freezer stay frozen when the power goes out?

#31

Post by Mathnerd314 » Mon, Aug 10, 2020, 2:57 AM UTC

pengaru wrote: post #18

A test with the freezer as full as possible with just water would be interesting as a best-case set of data points to compare against. I always keep containers full of water in the bowels of my refrigerators/freezers only removing them when the space is required for food. There's not much sense in keeping empty volumes of air in a refrigerated space.

When there's no airflow in the refrigerator, then it takes a long time to chill food, the reverse of how a blast chiller can chill food really quickly by moving lots of air. But maybe the water chills the air to make up for this, IDK. It would be interesting to experiment.

Re: How long does a freezer stay frozen when the power goes out?

#32

Post by k2xl » Mon, Aug 10, 2020, 2:58 AM UTC

pengaru wrote: post #18

A test with the freezer as full as possible with just water would be interesting as a best-case set of data points to compare against. I always keep containers full of water in the bowels of my refrigerators/freezers only removing them when the space is required for food. There's not much sense in keeping empty volumes of air in a refrigerated space.

That is a very interesting and clever idea. Thanks for the tip

Re: How long does a freezer stay frozen when the power goes out?

#33

Post by willis936 » Mon, Aug 10, 2020, 2:58 AM UTC

rsync wrote: post #9

Related ... the last time I was in the market for a chest freezer (a "deep freeze") I wanted one that showed a log of temperature over time ... This, essentially, does not exist. It appears that there are laboratory freezers that support this (very simple) feature, but they are relatively small and very expensive . A better way to go is an electricity monitor on the plug, where you track electrical power over time an…

I personally think the raspi approach is fine. If you want off the shelf, there are temperature and humidity loggers that are cheap. They’re typically wifi based and host a webpage. Some even come with probes so you don’t need to have the antenna inside a Faraday cage.

Re: How long does a freezer stay frozen when the power goes out?

#34

Post by foota » Mon, Aug 10, 2020, 2:58 AM UTC

pengaru wrote: post #18

A test with the freezer as full as possible with just water would be interesting as a best-case set of data points to compare against. I always keep containers full of water in the bowels of my refrigerators/freezers only removing them when the space is required for food. There's not much sense in keeping empty volumes of air in a refrigerated space.

Interesting, the idea being that the air gets cycled every time you open the door?

Re: How long does a freezer stay frozen when the power goes out?

#35

Post by jonathankoren » Mon, Aug 10, 2020, 2:58 AM UTC

rsync wrote: post #9

Related ... the last time I was in the market for a chest freezer (a "deep freeze") I wanted one that showed a log of temperature over time ... This, essentially, does not exist. It appears that there are laboratory freezers that support this (very simple) feature, but they are relatively small and very expensive . A better way to go is an electricity monitor on the plug, where you track electrical power over time an…

I had this very discussion on Twitter a few days ago, wrt "smart" refrigerators. The one thing that would be legitimately useful would be a batter back real time clock and thermometer, to alert you when the power went out, and what to throw away. I'd be shocked if this feature exists on any refrigerator. Not because it's difficult (It's not. Just monitor the temperature and print a stock FDA guidance), but because it's not what a product manager actually thinks of. Instead we get cameras inside, weather, Alexa integration, Google photos, just... bullshit features. Nothing that that anyone really needs.

Re: How long does a freezer stay frozen when the power goes out?

#36

Post by Torkel » Mon, Aug 10, 2020, 2:58 AM UTC

jacknews wrote: post #11

You want the contents to remain BELOW 0C, not hovering at 0C while everything melts. You can do this by adding some salt-water bottles, which have a lower melting point, and will therefore absorb a lot of heat (heat of fusion) well below 0C. Eg add 250g salt/liter gives melting point of -18C. Of course you waste some space on useless salt water vs potable - maybe there are better alternatives, eg fruit juice? Milk? H…

This is an interesting idea, would be great to see this tried with graphs.

Why don’t they do this with the ice blocks you get for keeping food cold on camping trips?

Re: How long does a freezer stay frozen when the power goes out?

#37

Post by oehtXRwMkIs » Mon, Aug 10, 2020, 2:59 AM UTC

pengaru wrote: post #18

A test with the freezer as full as possible with just water would be interesting as a best-case set of data points to compare against. I always keep containers full of water in the bowels of my refrigerators/freezers only removing them when the space is required for food. There's not much sense in keeping empty volumes of air in a refrigerated space.

I don't understand why that doesn't make sense. What you do with containers of water is what doesn't make sense to me.

Re: How long does a freezer stay frozen when the power goes out?

#38

Post by ghaff » Mon, Aug 10, 2020, 2:59 AM UTC

badRNG wrote: post #16

rsync wrote: post #9

Related ... the last time I was in the market for a chest freezer (a "deep freeze") I wanted one that showed a log of temperature over time ... This, essentially, does not exist. It appears that there are laboratory freezers that support this (very simple) feature, but they are relatively small and very expensive . A better way to go is an electricity monitor on the plug, where you track electrical power over time an…

> without resorting to weird solutions with raspis dangling temp wires into the freezer ... Well, I had a solution up till that line. There's gotta be an elegant way to set something like that up on top of the fridge out of sight with clean cable management into the freezer.

If you're going to bother--especially with a chest freezer--you probably want a number of temperature probes anyway. Just because there's been some thawing at the top/front doesn't mean that everything has thawed.

Re: How long does a freezer stay frozen when the power goes out?

#39

Post by fortran77 » Mon, Aug 10, 2020, 2:59 AM UTC

jacknews wrote: post #11

You want the contents to remain BELOW 0C, not hovering at 0C while everything melts. You can do this by adding some salt-water bottles, which have a lower melting point, and will therefore absorb a lot of heat (heat of fusion) well below 0C. Eg add 250g salt/liter gives melting point of -18C. Of course you waste some space on useless salt water vs potable - maybe there are better alternatives, eg fruit juice? Milk? H…

Vodka.

Re: How long does a freezer stay frozen when the power goes out?

#40

Post by golem14 » Mon, Aug 10, 2020, 3:00 AM UTC

rsync wrote: post #9

Related ... the last time I was in the market for a chest freezer (a "deep freeze") I wanted one that showed a log of temperature over time ... This, essentially, does not exist. It appears that there are laboratory freezers that support this (very simple) feature, but they are relatively small and very expensive . A better way to go is an electricity monitor on the plug, where you track electrical power over time an…

that's a great DIY project for an esp8266 and a temperature probe. Could even be a kickstarter. Everyone with kids worries about them leaving a fridge or freezer open.