Temperature-controlled Peltier Mini Fridge

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UPDATE: Project featured on Hackaday.com! See here
I recently finished up on my Peltier Mini fridge project, and it works great!
It can cool down whatever you want that’ll fit in it — six 330ml cans for example — and can get down to –2.1°C!
Watch the video for a full description and how it works. I gotta say, it’s really cool, excuse the pun!


It is built using a Peltier Thermoelectric cooler module which is a ceramic plate but with many p and n-type semiconductors placed in series inside it. Here’s an image of one:
peltier_cooler
When powered, it acts as a heat pump where one side becomes extremely cold and the other extremely hot. To make use of the cooling a heatsink will need to be put on the hot side to dissipate the heat which is being removed from the “cold” side.
When this is done, extremely cold temperatures can be reached. When running at 12V and 3.5A, I measured around –15°C on the bare side, although you could go colder with more heat dissipation on the hot side and a more powerful Peltier cooler module.

With the heatsinks mounted (be sure to use thermal paste!) and a suitable polystyrene enclosure chosen, everything fit together perfectly and worked great.
topdown

To control temperature a temperature controller was purchased from eBay, here is what it looks like installed:
temp_controller

It is powered by the 12V supply and the relay output switches the Peltier cooler module and fans, and can maintain the temperature quite well. Its thermistor probe is located inside the cool box for reading the temperature as seen here (the cylindrical probe on the left):
inside

I powered it using a modified ATX power supply from an old computer, for the 12V output. The fridge draws around 3.5A when the Peltier module is on.

Resources list:

  • Peltier cooler module: eBay
  • Temperature controller: eBay
  • Heatsinks – salvaged from old computers and electronics, otherwise at computer stores.
  • Power supply – I would recommend a 12V power supply capable of supplying 5A of current as it’s generally a bad idea to operate power supplies at near full capacity for long periods of time, so 5A is a good figure, these shouldn’t be too hard to find; I actually used a PC ATX Power Supply that I modified to give 12V output, found in any desktop computer or at computer stores. Instructions to modify. These can supply >10A so more than enough power for this project – they could actually run a few Peltiers.

This project worked out great, although many Peltier fridge projects fail as they don’t end up reaching the desired temperature. A common problem is not having proper insulation or the enclosure being too big for the size of Peltier module they are using. Don’t oversize it — unfortunately this system will never be as efficient as a standard refrigeration system with a compressor, etc. however it is very cheap and easy to build, as well as near silent.

For me it gets the job done and it’s worked well on a camping trip already! A huge success.

17 Thoughts on Temperature-controlled Peltier Mini Fridge

  1. Hey, I would love to know exactly which components you used. While the ebay searches are helpful, I would like to be able to look for the same components, both on ebay and other places.

    1. TheOneWithNoName,
      The components used aren’t really all that important, you should be able to adapt a version to work pretty easily.
      However if you want I found an assembly with the peltier, heatsink and fan preattached: http://www.ebay.com/itm/Thermoelectric-Peltier-Refrigeration-Semiconductor-Cooling-System-DIY-Kit-Cooler-/261792872834?pt=LH_DefaultDomain_0&hash=item3cf4123982.
      Here’s a temperature controller which would work: http://www.ebay.com/itm/50-110-C-DC12V-Heat-Cool-Temp-Thermostat-Temperature-Control-Switch-/400677190587?pt=LH_DefaultDomain_0&hash=item5d4a38bbbb

  2. Dude, that is a sick (meaning totally awesome) video. Can it be adapted with an inlet and an outlet for a water pump to pump water in and chill it and then pumped back out? The pump would be pumping out 250 GPH, but the total mass of the water would be 8.33 gallons US being pumped through 2 – 5 gallon buckets continuously.

    1. Hi Mark, thanks for the kind words!

      To be honest, the Peltier setup in this video just can’t provide nearly enough cooling for that application.

      However, it can be done, and cheaply! What I would recommend is to get an office-style water cooler (bigger is better, but a small one should work, just try to get a bigger one), but key is it must be compressor-driven, as these can deliver a lot more cooling than Peltiers. Some small ones are Peltier cooled so watch out you get the correct, compressor-driven one. Look at second-hand stores or craigslist, etc. 😉

      They have a water-reservoir which pre-chills some water – sort of like a hot water heater – just below where the bottle would go so simply put your tubing in the reservoir and circulate to get your cooling. This is something people do with their aquariums, it works pretty well! Here’s an article on how to make one.

      Note, since the compressor will be running for extended periods of time, I would strongly recommend you install a decent fan(s) to blow against the condenser (hot) coils and the compressor – you don’t want this to burn out, and to ease the load, use ice to get the water chilled quickly so the water cooler just keeps it cool. Also try to insulate your buckets and pipes as far as possible as this makes a BIG difference! If you have foam just wrap the buckets in them, that should work.
      I think such a system should be able to keep the 8.33 gallons chilled, or at least at a low temperature for a looong amount of time (very slow temperature rise). The less water, the better the cooling, so worst case scenario reduce the volume of water. Additionally since the volume is so small anyway, I would guess a 250GPH pump is way overkill, you could use an aquarium/fountain pump and just put it right in the water-reservoir, like in the blog post linked earlier. The slower the water flow, the more cooling can be delivered due to thermal contact of the walls of the reservoir to the water inside it – too fast, and there won’t be enough time for the heat to be transferred.

      I wish you good luck with the project, it sounds awesome! Please let me know how it goes or if you have any more questions, just use the contact form. I’m interested to know more about it too, if you could just send some project details as it sounds awesome!

      Regards,
      Joseph

  3. Joseph… this type of thing may be just what I was looking for. For my particular application, I would like to be able to either cool my terrarium or heat it, in order to keep it within a narrow range of temperatures. I read something that implied you could switch the polarity of the current to get it to supply heat when the enclosure was too cold. Did I get the right impression?

    Do you think it would be easy to rig up such circuitry? I don’t have a shop, nor any significant background in electrical design.

    1. I would also like to see a circuit diagram. Also, would I be able to use two modules by putting it through a 2 channel relay.

  4. hola.
    estoy utilizando una celda peltier y funciona muy bien pero a la tercera vez que la voy a utilizar la corriente de consumo disminuye y no enfria nada y con otra sucedio lo mismo. mi pregunta es: necesita algo mas aparte de la pasta termica el disipador y el cooler para su funcionamiento, ademas la fuente es de 12 voltios DC Y 17 amperios y la celda es de la misma referencia que ud utiliza en el video. Gracias

  5. Hi Joseph, thanks so much for sharing your fridge! I am not very mechanical, but I think I almost have it after watching your video three times. Just a few questions please. What is the blue thing you use to create space for the styrofoam wall to extend the heat side of the heatsink? Are the fans just computer fans or are they peltier thermoelectric fans? Please get back to me. Thank you, Adam Walker

  6. Hello ..
    I was impressed by your idea …
    But can you give me an idea or way … How to Make a refrigerator in my car in the back seat …
    Knowing that my car Volvo 850 T5-1997
    Or direct me to any page of the workshop tuning on the Internet …
    thank you very much …

  7. Hello Joseph,
    Could you please help me with the power supply specs as like we are going to use 12V 8A power supply, why to use this, its compatibility with the peltier module project.
    And also please tell about the different power supply ratings available that could be used for this project.
    Thanks
    Bhishan Mittal

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