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Comment by contingencies | Hacker News Reader

It depends on the thermal mass of the contents, the effectiveness of the insulation, and the external ambient environmental temperature.

In real world use, it also generally depends on (1) how frequently and for how long you open it, and (2) whether it's top-loading (efficient) versus front-loading (inefficient).

Source: My venture custom designed and built a refrigeration circuit with autonomous electronic management from scratch over the last year or so, so have done numerous recent tests in this space. I also visited about 4 different fridge factories in Guangdong and spoke to their engineers, investigated the different available chemical coolants, relevant sensors, etc.

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Hm did you read the article? I ask because you're just repeating things brought up in it.

> My venture custom designed and built a refrigeration circuit with autonomous electronic management

Is that a web 2.0 way of saying a thermostat?

It's probably a web 3.0/IoT way of saying an ESP8266 with a couple of sensors and a relay. From there you could do some slightly smart stuff like observe the rate of warming towards ambient when idle (i.e. determine the volume of material in the freezer) to determine how long you can go without running the compressor. And from there you could manipulate the thermostat's target depending on current and future predicted electricity prices.

With a load sensor attached to the tub, you could determine when a substantial volume of new material has been added and preemptively run the compressor hard for a bit.

Many things are possible. Most of them not worth the complexity.

Yes, given the thermal mass of a fridge any type of advanced control is probably pointless.

I think late 90s/early 2000s was the peak of fridge reliability to efficiency ratio.

They run the defrost timer through the thermostat, so defrost cycles are somewhat inline with fridge use.

The circuitry is simple - a defrost timer, PTC "relay", a few thermostats and the compressor.

Newer fridges are a bit quieter and more efficient with inverter technology, but failure rates are way higher due to electronics failures.

Well, theoretically you could just use 3-phase motors, right? I'd actually like that, and over here in Germany, most homes have a 3-phase supply in the kitchen for an electric stovetop.

Hmm not sure why a 3 phase motor would make a difference?

More efficient than single-phase. In this case, it makes the inverter redundant, because the inverter's only purpose is to produce a 3-phase AC supply for the motor.

I.e., you can cut the sensitive electronics out.

I keep a coffee mug filled with water in the freezer with a penny on top.

Have you seen how long this setup takes before it'll trigger a change? Ive left glasses of frozen water to thaw and they most definitely don't thaw evenly. They also take way more time to thaw than any regular food product due to the significant heat/surface area ratio difference.

I wish my freezer wuld have spare space for mug filled with water

I keep my freezer at least 90-95% (you may think 5-10% is enough for cup, but it's just small flat space available among drawers) full pretty much all the time, it keeps it running at highest efficiency and also you have always maximum available amount of food in case of lockdown for instance

Are you sure that will drop the moment the water thaws?

(https://www.usmint.gov/learn/educators/lesson-spotlight/make...)

Wouldn't the pressure from the penny bias your observatios from the mug?

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