Mini Fridge





Introduction: Mini Fridge

So this guy at work got a neat little mini fridge for a can of coke. I thought to myself "I can make one better than that". And so my home made mini fridge was born. It has 3 peltier coolers enclosed is a 4 inch diameter pvc T joint. It's powered (underpowered by about 120 watts) by a 55 watt 5 volt power supply. The power supply was only $6.00 and I couldn't find one more powerful that fit my specifications and was relatively cheap. It cooled the inside down to 68 F when it was 96 F outside. I took it inside and it cooled down to 46 F. Unfortunately I didn't think to make an Instructable until afterwards. I haven't actually made an instructable yet but I think I've got a good one brewing. In the mean time, here are some picture.



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    I know that it is really really annoying when you have made something but didn't think to make an instructable until after you have made it.

    whats the biggest space a 12v 230w Peltier unit could cool down

    *overkill* lol


    i have a question, i basically have very little knowledge in electronics. Will it be a problem to have a power supply lower/higher Amps than my peltier? what if I have 2 or more peltier and power it up straight to the power supply will it equaly have the same voltage, or i have to do extra wiring for multiple peltier?

    7 replies

    Overpowering any device can be fatal to the device and power suplies life. It's always recommended to stay within operating parameters. If you need more out of peltier junctions, I would suggest to use more of them or use ones that are rated for higher power. I found the most drastic increase in effectiveness was by making the insulation better. This old thing I made was 3 coolers off of one power supply connected in parallel.

    actually ive found that using a computer power supply is the best because the computer supply wont force in more current than the peltier can handle, i use a 430 watt supply with a 168 watt peltier and it works perfectly

    Have you measured the actual voltage and amps going through the peltier? And are you using one of the 12v rails. I've never tried it with a pc power supply so I'm curious what it would actually draw power wise.

    yes ive measured the amperage and it is only pulling about 8 amps at 12 volts, and i am only using one 12v rails out of 2.
    the TEC specs are Vmax 15.4v Imax 11A resistance 1.16 ohm.
    Do u have any ideas on how get the TEC to use full amperage, because if i am correct then the TEC should use 14 amps at 12 volts.

    The limitation is most likely the power supply. Peltier coolers have no limitation in what voltage or amperage you can push to them. Too much power and they will fry of course. It may be a 430 watt power supply but thats for all voltage rails combined. Check the label and it should say the max amperage for the 12v rail. I have a 450watt and the 12 volt rail is rated for 16 amps. Under load it only puts out around 11 though. As with most components, pushing them to their max power levels usually will decrease the life span. I don't like buying stuff that burned out so I usually under power everything. So 12 volts at 8 amps has a lot of head room but I'm honestly not sure about the performance difference. You should measure the temp for the current power level and see if there is a big difference if you can get it to the 15 volts at 11 amps.

    yes I think you may be right as one 12 volt rail offers 14 amps and the other offers about 16 amps. so it is most likely the supply that is limiting the amperage. Do you think it may be possible to link the two 12 volt rails in parallel for more power delivery or would i risk frying the power supply?

    I don't really know too much about pc power supplies. It could very well fry it. I know I've used wall wart power supplies at varying voltages and amperage in parallel and they didn't fry. But pc power supplies are pretty refined in their output so changing that may have a bad reaction. You may want to ask that in the instructables forum and maybe someone there has tried. A quick google search and it looks like people say it's possible and works but take that at your own risk.

    Alright... I just have a few questions, How many peltiers would you recommend for a 2 liter soda bottle holder? How is it in a not so well ventilated space? How long do you keep it on, how many hours (or none) straight? Thanks

    5 replies

    Two liter bottle, Two or 3 peltier coolers would do fine as long as you have the proper insulation for the container. Mine would have worked a lot better if I used something that actually insulated (PVC sucks at that). More coolers will cool quicker but not necessarily get it colder. So how many depends on how quickly you want to cool really. Ventilation is a big part for the hot and cold sides. The hot side for it's obvious reasons. It doesn't have to be well ventilated honestly, but the better cooling for the hot side, the colder the cold side gets. So less ventilation will obviously just be a warmer result. Ventilation for the cold side is also a big deal. At the time, the cold side of my coolers were flat metal plates. This worked...but slow. I added heatsinks later and it cooled much quicker. Heatsinks help the flow of heat by increasing your surface area. So adding heatsinks to the cold side effectively helps pull heat out of the air inside the cooler at a much faster pace. I kept the unit on solid over 24 hrs testing it, never had an issue. I never actually ended up using it because it looked questionable. I dismantled it in an attempt to make a more safe for work look, but it still was not something I'd want to take in to my work place so the project has been scrapped.

    Also I almost forgot to ask where you got your power supply? Thanks again

    I bought it from

    But as I looked this up I saw another good looking power supply if you plan to run multiple peltier coolers:

    Most peltier coolers run from about 5 to 15 volts. But just make sure to check the specs on them before so you you don't burn them up.

    Thank you so much, I can't wait to start this project, Happy Thanksgiving by the way (unless you're not from the US).

    Thanks so much, sorry I didn't see that you replied right away. Wow 24 hours sounds great! looked.....questionable haha thanks for the info though.

    The only reason I ask about the ventilation question is because when one side of the peltier gets cold, one side gets hot, so basically how well did your heatsinks or fans do for the hot side? Once again thank you very much