I had a feeling portable mini-fridges were near useless

I bought one from B&M not long ago, and threw temperature sensors into it, and it couldn't maintain temperature, took ages to get to a low temperature, and it didn't reach the temperatures it claimed on the box. It claimed it could reach so many degrees less than ambient, it didn't.

I found this youtube channel, and it is pretty cool:

They pretty much come to the same conclusions I did, and then compare against "actual" fridges.

Mainly USA centric though.

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shabaz 11 months ago

Interesting.. I have a 'fridge like that, but I don't use it for drinks. It's in the shed (i.e. the fan noise isn't an issue there), used for storing solder paste etc., that I wouldn't want inside the home in the normal home 'fridge. It keeps things cool enough for that purpose, but I guess it's non-ideal for drinks storage!

Also the supplied mains brick is junk (lasts less than a year).. I went through a couple of those on warranty, before just buying a better mains adapter from Farnell. The 'fridge seems reliable, just not the mains brick they supplied. The fan won't last forever of course : (
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battlecoder 11 months ago in reply to shabaz

That's a very clever use for this kind of "fridge", actually.
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beacon_dave 11 months ago

There's always the WRONGCO brand Solar Powered Tropical Beverage Cooling Mug

/challenges-projects/project14/off-the-grid/b/off-the-grid-blog/posts/solar-powered-tropical-beverage-cooling-mug--blog-1---the-concept
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Matt 11 months ago

Technology Connections is a great channel; he goes into so much depth on everything he looks at; they're well researched. There are bunch of recent ones on old pinball machines if that floats your boat.
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battlecoder 11 months ago

Btw one of the things he mentioned in the video is that their efficiency is atrocious. Mostly because they are always ON. I wonder if you could "improve" on that regard if you added a thermoucouple and a low-power micro that would turn the Peltier element OFF when it reaches a target temperature and ON again once the temperature starts rising.

Maybe for small items the efficiency (when controlled this way) would be more acceptable. Because if it's going to use as much power as a full size fridge the only reason to NOT use a fridge would be the size (and price, but I guess it's always an option to get a second-hand mini fridge for cheap)
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DAB 11 months ago

This is another one of those products that fall into the "yes you can build it" category, but "no you should not."

The efficiencies are just atrocious.
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stanto 11 months ago in reply to battlecoder

battlecoder said:
I wonder if you could "improve" on that regard if you added a thermoucouple and a low-power micro that would turn the Peltier element OFF when it reaches a target temperature and ON again once the temperature starts rising.

I experimented with this on one of these mini fridges I bought.

A significant problem is that it takes a very long time to get to the target temperature, and then it loses it very quickly once the peltier is turned off, suddenly it's got a large amount of heat that it can't get rid of very quickly on the attached heatsink, and the generation of chill has stopped.

In the video he also shows that the insulation of it is terrible, styrofoam in the walls, but nothing in the door. This might help if it changed, but not a great deal.
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James123 10 months ago

This is something that would go on my "I wouldn't buy it even if I had the money" list.
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