Peltier Mini-Fridge Preserves Chip Quik, Marriage

[Charles] uses Chip Quik to solder his SMD parts, and that stuff can keep for more than six months if it’s kept cool. His wife banned all non-food items from their refrigerator, so he had to think fast and came up with this Peltier effect Chip Quik cooler.

He first looked into that man cave essential, the mini-fridge, but they’re too expensive and use too much power. [Charles] got a nice wooden box from a hobby store and some reflective insulation from Lowe’s. He first tried using a couple of heat sinks but they weren’t going to cool things down enough. Once he got a Peltier cooling kit, he was in business. The temperature in his workshop averages 80°F, and he says the box gets down to 58°F. This is cold enough to keep his paste fresh.

[Charles] plans to use a PC power supply in the future rather than his bench supply. He estimates that his Peltier cooler uses 25-50% of the power that a mini-fridge would, and now his wife won’t overheat. Many great things can be accomplished with the Peltier effect from air conditioning to sous-vide cooking to LED rings. What have you used it for?

Comments

  1. butterfly says:

    $20 on craigslist is “too expensive”?

    Does every single post have to have such ridiculous hyperbole in an attempt to justify the hack?

    Yes, I realize this post is basically plagiarized directly from the blog post, but maybe use a little journalistic judgment next time.

  2. Chris T says:

    You can get a small minifridge at Wal Mart for $49 on sale sometimes. That’s too expensive? And power consumption is like $20 a year. A peltier is several times less efficient than a refrigerator.

    • jan says:

      Not to mention that a typical peltier needs several amps of power and the heatsink gets quite hot. Not the sort of hack I would want to be running non-stop unless it is done properly (fire hazard) – but then you could buy that minifridge as well …

    • Pat says:

      The Peltier isn’t the problem. Plenty of tiny fridges use peltiers. The problem is the fact that it’s not well insulated, at all – it’s the insulation that does pretty much everything. A cheap thermoelectric cooler is perfect for this: you have no thermal mass, so you really don’t need a serious amount of power, and the reliability’s higher.

      Heck, even one of those cheap USB mini fridges would probably be fine, especially if you made something like a ‘can’ for the paste that you left in the fridge so that it could cool down the paste quickly after you’re done using it (n.b., you could do the same here). And they’re like $20. And use like, 5-10W or something.

    • static says:

      To state the obvious “too expensive” is relative. Anyone who took the time to read ‘s blog would have learned that size is a factor. True Peltiers aren’t the mos efficient means of heating and cooling, and again those who read Charles blog learned “… It’ll take about 25%-50% of the power of the smallest frig I could find…”, so for Charles needs it’s energy efficient. No one is saying you have the room and afford to purchase WM special, you shouldn’t. Hell with the school year ending soon there may be students selling their mini refers so to have less to haul home

  3. J.C. Wren says:

    “Banned non-food items from their refrigerator”? Has she accidentally eaten non-food items in the past?

    That’s where I keep solder paste, film, etc. They are in labeled zip-lock bags, but mostly just to keep any additional moisture out…

  4. Jonathan says:

    I’m really confused about the two heat sinks…. The one in the box had a fan, the other one didn’t, OK. This was before the peltier cooler though, so what was he trying to accomplish, besides thermal equilibrium between the inside of the box and out? How did the outside heat sink even get warmer than the inside one? (I don’t know how he wrote this, or how Hack a Day copied it without wondering this themselves.)

    Anyway, cheap-o mini-fridges are just peltier devices themselves, and are wildly inefficient compared to compressor based fridges. He just built wildly inefficient version of one of those. What’s going on here???

    • Tony says:

      Here’s an article from over 10 years ago: http://www.k3pgp.org/sales/ck1500.pdf (yeah Peltier fridges are old news) that actually explains stuff, unlike the blog.

      The internal heastsink is to improve thermal transfer, in the linked article they use a flat plate (a heatsink would take up too much space).

      Peltiers, while rather neat are generally rubbish. They do have their uses though, most posters here missed the comment that he built this because he did have the space for a mini fridge.

      • Jonathan says:

        I’m asking about these lines:
        ”’The inner heat sink had a fan, exterior heat sink didn’t but didn’t get uncomfortably warm. It didn’t work as I had hoped though; I couldn’t pull off more than about 10 deg F delta T from the ambient temp in the room”’

        In the paragraph following that, he decides to buy a peltier, so the two heat sink setup didn’t involve a peltier, just a fan, and “couldn’t pull off more than about 10 deg F delte T”. I’m pretty sure someone is breaking a law of thermodynamics here.

        • Tony says:

          I think it’s just poorly written.

          Seems he had a Peltier on the first try (the ‘failure’ in the photo), but putting a fan inside the box is a bit of WTF. If he tried just two heatsinks and a fan inside and then wondered why it didn’t work… yeah well.

          The Peltier on the failed version was probably too small (or he had the voltage too low). The big heatsink on the hot side was a good start.

          The thing about Peltiers is the external heatsink can never be below ambient, and the cooler you can keep that side the better. 25C is good. As the Peltier temperature rises you get a reduction in amps flowing (max amps = max cooling) so it’s rare a Peltier ever runs at it’s peak. (You also need to run them at max volts, say 15v to get max amps as well.)

          In theory you can get 70-80C difference between the hot & cold, in practice not so much. The 10C degrees difference he reports is ok, but you wonder if it’s worth the effort (just put it in the cellar). You could get that with a simple evaporative cooler.

          I tried the Peltier approach once and could get 30C difference, but that was with two 90W panels, big heatsinks and big fans.

          Buying a cheap fridge was a better solution all round.

          • Tony says:

            I should point out that those 90W Peltiers are rated 15V @ 6A, you use a lot of power for little reward.

            They’ll never draw 90W but anyway. Then you realise a fridge compressor is about 100W and junk the Peltiers.

            They are fun though. Get people to hold them, apply power and then reverse the wiring. Magic!

    • Pat says:

      Thermoelectric fridges are only ‘inefficient’ if you compare power in versus heat extracted. There, of course they stink. But if you compare just *power*, period, the small fridges can be more efficient, just because it’s not practical to make a tiny compressor-based fridge.

  5. Brian Kamusinga says:

    The heat sink is of a similar size and shape to one I once took out of a minifridge, if indeed it was from a minifridge , isn’t this hack an exercise in futility, breaking an efficiently insulated part for a worse one?

  6. 0xfred says:

    The cheapest and most energy efficient option is to use the fridge that’s already running. He needs to man up and tell his wife that a little bit of solder paste in the corner of the fridge shouldn’t be a problem.

    What’s his next project? Something that puts the toilet seat down after he’s peed so that she doesn’t shout at him?

    • Greenaum says:

      Just wait til those efficient, low-noise, robot wives get cheap enough. She’ll be lifting the seat up for him and holding his wang for him with silver tongs.

  7. fartface says:

    “but they’re too expensive and use too much power.”
    He did not look very hard.

    There are tons of them all over amazon and ebay that are run by peltier. $19.99-$59

    and if $59 is too expensive, then I suggest he get’s a new hobby. I dropped $499 on my stereo microscope upgrade last week. And I am eyeballing an upgrade to my hot air rework station.

  8. Natalie says:

    Though I understand the tongue in cheek nature of this HaD post; this post is just a poor attempt at trolling. HaD said “banned”, when after reading the original article, it was a mutual decision between the author of the original post and his partner.

  9. Avel says:

    She sounds like a

  10. kristian says:

    Reasoning and practicality aside, the title made me chuckle.

  11. bryan says:

    fact error: chipquick is an UNSOLDERING thing and its solder paste that has a lifetime and aging issue. solder paste is for SMD work and does have a ‘freshness’ to it; but chickquick has no lifetime aging issue at all; its just a special allow metal with a melting point that stays liquid longer, to help you remove items soldered from a board.

  12. bryan says:

    btw, I find it sad that the author does not know the diff between soldering and unsoldering; but worse, HAD didn’t even bother to read the article and realize that CQ is used for removing smd items and not soldering.

    how did you guys pick your ‘story editors’? do they really understand hardware or are they just english majors parading as techies?

  13. bryan says:

    cq is a brand but when engineers say ‘chip quick’ they are pretty much entirely talking about the low melting point REMOVAL technology, not the soldering-on technology. CQ may have expanded their product lines but no one talks about CQ being a solder paste.

    solder paste is its own term and is not tied to a brand. the brand CQ pretty much entirely means ‘unsoldering’, in the parlance of our times…

    • RunnerPack says:

      Ah, yes… the classic “but everyone does it” defense :P
      Maybe if you had your own company, you wouldn’t be so quick to pigeon-hole others’ and then attempt to justify said action in Internet comment posts when your lack of knowledge is exposed.

  14. big-j says:

    Please check the date of the original article folks…………. (sighs)
    :)

  15. spiderwebby says:
  16. Bogdan says:

    If the post is meant to be serious, why not a water pipe/hose loop between the fridge and an exterior box?

    Also, it is stupid to compare the power usage of a refrigerator and a peltier directly. A 100W peltier will probably move 30W of heat, while a 100W compressor refrigerator will move 300W of heat.

  17. deathventure says:

    1.7/1.8 cubic foot mini-fridge around the $60USD mark. Efficiency is lost due to lack of insulation as somebody had mentioned already.

  18. mr butts says:

    BTW chipquik sells rebranded Amtech solder paste, not just their own bismuth desoldering stuff. And legit Amtech is very good. Fakes abound

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