Nov 122021

It all started with hurricane Ida, or probably Katrina, but Ida restarted it. I remembered how much it sucks to not have power for a while and how much difference a little ice and a fan makes.

I’ve been down this road before. Katrina sent me down rabbit holes that led to free-piston sterling coolers, peltiers, vortex tubes, and of course evaporative cooling. But life and laziness prevented me from doing much about it until now. Long story short I got a DC portable freezer, an Aplicool C-20 that’s about 20L and supposed to be able to get down to -4F. But I think that’s probably rated in Michigan where 60F is a hot day or something, it struggled in my 76F apartment but it was pretty obviously an insulation problem because the exterior got really, really cold.

I considered ripping the whole thing apart and rebuilding it but I figured there was a good chance that could end with no freezer and a bunch of trash so I decided I’d do something probably crazier and just build more insulation around the cooler. Kind of problematic to insulate 3/4 of a rectangle when 1/4 is generating heat, but I figured it might work, so I built this monstrosity.

And surprisingly it freaking works. Without the extra insulation it will freeze water and get to about 20F, but it’ll stay there and run the compressor forever. With the foam it goes all the way to -4F and cycles the compressor on\off. I haven’t figured out the duty cycle and the actual gains but it’s an obvious improvement.

So yay, I did a thing that worked out the way I semi planned… now what? I don’t really have much use for it in an apartment so it goes in the stack of gear I made but will never actually use. Actually pretty huge addition so it’s at the bottom of the stack… anyway- it is what it is. If\when I get a tinyhome it’ll be great to have.

But the unexpected lesson I learned from this exercise is that this pink foam shit is pretty awesome. Very, very strong and workable and insulates like nobody’s business, and I had like 3 extra 2’x2′ sheets of it.

So I made more mostrosities.

This is a mini cooler that holds 2 square instant Community coffee things. They’re great because they’re square, and I use the coffee anyway. They work sort of like those old hard freezer packs. Not sure why I made this but I kind of wanted to see how long they’d stay frozen with 2″ of foam. The answer is about 3 days in an apartment between 70-80F. I was impressed.

Another one… this one was because I got into the idea of ‘directional freezing’ so I can make perfectly clear ice. But I initially misunderstood the idea so and just thought I was supposed to slow down the freezing, but there’s more to it. So this doesn’t work and it’s basically a really great cooler for about one or two big ice cubes.

I’m still not entirely sure what I’m up to here but there’s a peltier chip involved. I did finally learn that controlling peltiers with MOSFETS is way more trouble than it’s worth and there’s no shame in just slamming it on-off with a relay like a normal human being.