How to build a Peltier cooler

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Rammplins

 
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How to build a Peltier cooler

by Rammplins » Mon Dec 11, 2017 7:19 pm

Here is a small guide on how to build your own peltier cooler, mine is built as described and manages to get my 10g tank down to 54-56 F every night without problem. For 50$ it is much cheaper than getting an AC or effective swamp cooler, plus it takes up less space.

(Disclaimer: I am not an electrician, just a guy who likes to learn about sciencey things. Please be careful and use common sense with electronics, don't mess with wires while your unit is plugged in.)

Note- in the future I will be making another peltier cooler, when that time comes I will update this with step-by-step pictures and real world views of the wiring.


Terms:

Volts (V) - the electromotive force - the volts in your system must NEVER BE HIGHER than what your equipment can handle. For example if you have an 18V fan and a 12V fan on the same circuit then your max V would be 12V. 18V would burn out the 12V fan by delivering too much power.

Amps (A)- Amount of current - The amps in your circuit must ALWAYS be higher or equal to what your equipment calls for, higher is better. If your amperage is too low than your equipment wont turn on and you will burn out your power supply.

Watts (W)- amount of power - the formula to find your wattage is (V) x (A) = (W). You ALWAYS want your power supply to have MORE watts than your circuit takes, or else you will burn out your power supply.

PSU- Power Supply Unit

LEAD- is an electrical connection consisting of a length of wire that comes from a device. (Basically the end of a wire that will connect to something else)



Lets start with what a peltier is:

A pelter is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current.

Temperature differential: this is the maximum difference in temperature between the two sides of the peltier.
-this will never be an exact number and will change with the amount of amps/volts in the system. The differential for different amp/voltage combinations can be found on the manufactures datasheet. (but you really don't have to worry about it, unless you want exacts)

Example:

Lets say your peltier has a differential of around 20 degrees, and the hot side of your peltier measures at 60 degrees, this means that your cold side will be around 40 degrees.

Therefore the better cooling system you have for the hot side, the colder the cold side will get.





LETS GET STARTED!


For this project you can go out and buy an already put together peltier cooler for around 40$, but don't. I have found that the quality will be much higher if your bulid it yourself, plus most of the pre-built peltier coolers on the market don't have fans/ heatsinks that cool down the hot side enough for what we need to use them for or are way overpriced for what they are.

Here are my materials: comes out to around 50$

Materials:

2- small 40mm PC fans

2- small 40x40mm finned aluminum heatsinks

2- cpu coolers, the more copper heat pipes the better

2- tubes of thermal grease. the higher the W/mK (speed of heat transfer) the better, mine is 3.3 W/mK

2-3 PC fans, size 80mm or larger. mine have 38.2 CFM (amount of air flow) and work just fine (if your PCU cooler came with fans than you don't need these)

1- 12V D/C power supply with at least 15A (it is very important that the power supply outputs in D/C)

1- electrical tape, superglue, c-clamp...ect. something to keep the pieces together

10- Wire butt crimps/ wire caps / or solder

1- spool of 16-12 gauge wire

2- TEC1-12706 peltier units


Optional: (this will save you from striping the leads off of your fans and is easier to use if your fans have 4-pins)

1 or 2- Molex Y-slpit to 3/4 pin pmw (for fans) example:
https://www.amazon.com/CRJ-4-Pin-Molex- ... wer+supply


Tools:

-Soldering gun/ wire crimper/ screw on wire caps

-Glue gun

-Wire stripper

-Wire cutter

-small spatula/ old credit card/ hard flat object

(I use wire crimpers and butt connectors, bought together for 6$ and the crimper included a wire stripper and cutter.)



Creating the cooler:


First take your two 40mm fans and hot glue them to the bottom fins of the 40mm heatsinks,. Make sure they direct air flow down and away from the heatsink, not into the heatsink. This is the piece that is acting as a cooler for your tank, pointing the air toward the heatsinks will greatly reduce its effectiveness. DO NOT USE SCREWS TO HOLD IT IN PLACE! they will rust quick due to all of the condensation, and then start dripping high ppm water onto your plants.

next put some thermal grease on the top of the 40mm heatsink where your peltier will go, spread it around evenly with the spatula/ credit card. Do the same with the cold side of the heatsink, and then gently place the peltier on top of the heatsink and press it down to create a seal.

Next cover the hot side of the peltier and the bottom of the pcu cooler (the pcu cooler may already have thermal paste applied, if so leave it be.) in thermal grease as explained in the previous step. Place the cooler on top of the heatsink and gently push it down to create a seal.

now to test them, plug your peltier into the power supply and feel the heatsinks to make sure you have the correct side facing the right way, the small side should be getting cold, and the large side should be getting warm. If everything feels correct then unplug it and secure the peltier to the heatsinks using the electrical tape/ superglue/ c-clamp... ect. and let it sit to cure for 12 hours. trying to use or move it before then can result in the peltier/ heatsinks sliding out of place due to the viscosity of the thermal paste.


Wiring:


Basic parallel wiring Principals:


In a parallel circuit all voltages are the same, no matter how many devices are on it. The Voltage of the system is dependent on the voltage of the power supply. if you have a 12V power supply, then all of your devices on the circuit will be supplied with 12V.


In parallel circuts the amount of amps each device pulls is added together. So lets say we have 3 fans:

2- 12V .5A fans

1- 12V .3A fan

adding the amps together (.5+.5+.3) gives us 1.3A - this is the absolute minimum amount of amps needed to run the system.

If we put this number into the equation for watts:

(12V) x (1.3A) = 15.6 Watts

So for this system you would need a 12 Volt power supply that has at least 16 Watts.


How to wire a parallel circuit:


Yellow, red, and black with white stripe are the normal colors for indicating that a wire is on the "hot/positive" side


Black-only cables are almost always used as the "cold/negative" side


Before you start make sure all wires are clearly labeled and stripped, switching one of the wires can cause a short that will probably fry the device that was wired backward.

-If you got the optional molex connector then the connectors one side will fit right onto the fan, the other side has a large trapezoidal block attached to it, if you look on the block where the wires are going in pin-1 is positive, the ones in pin 2 are negative. Be sure to mark them and then cut off the large piece as close to the base as you can.



the wiring for parallel circuts is fairly easy and straightforward. All negative ends from the cooler will wire into the negative side of the PSU, and all Positive ends will wire into the positive side of the PSU.


-Fans: wiring there will be the hardest part, if you got the optional molex connector then it is a little easier. If you have 2-pin fans those are straightforward, one wire is positive, one is negative. 3-Pin fans have whats called a "sense" wire that is usually yellow, but can differ from fan to fan. To make these work without buying the molex connector- separate the negative wire from the bunch, then strip and twist the remaining 2 wires together. This will be your positive. Don't even ask about 4-pin fans, i'm still having trouble figuring out how to wire these without using connectors, just use the Molex connector.



Starting your wiring:

LEAVE EVERYTHING UNPLUGGED UNTILL IT IS TIME TO TEST YOUR UNIT!




1. Find all of your positive wires from the cooler, Take your 2 positives from the fans, twist them together place them in one end of the butt connector, then crimp the connector on them


Example:
20171204_152146.jpg
20171204_152146.jpg (3.02 MiB) Viewed 1085 times



then do the same for your 2 peltiers, and then 2 small fans. You should now have 3 positive leads coming form the cooler. (2 from fans, 1 from peltiers)


2. Do the same thing for all negative leads, You should now have 3 negative leads from your cooler.


3. Next take your spool of wire and take as much wire as you will need to reach your PSU (while it is plugged in) from wherever you will be keeping your cooler and cut it to length. Then take this wire and strip both ends, Then attach the hot/cold connections at the PSU


Example:
20171204_161514.jpg
20171204_161514.jpg (3.06 MiB) Viewed 1085 times


4. Make sure your wire reaches your cooler, then cut three 6" pieces of wire from off of your spool and strip both ends of each. On one end take each of the positive wires, twist them, and connect that end to the positive wire coming from the PSU. Do the same for the negative wires

Example:
20171204_161522.jpg
20171204_161522.jpg (3.21 MiB) Viewed 1085 times



5. Connect the remaining positive ends from the cooler to the PSU, then do the same for negative wires.

Example:
20171204_161527.jpg
20171204_161527.jpg (3.37 MiB) Viewed 1085 times



Everything should be working now, plug it in to test it out. You should feel it start to cool or heat up very soon. If everything works unplug it, check for loose wires, if you want to put some hot glue around the ends of the butt connectors for extra protection and you are done.


Congrats on your new peltier cooler!


When installing your cooler into your tank it is very important that only the cold heatsink is in your tank. If you throw the whole thing in there it wont do anything, luckily most cpu coolers come with a stand or ring to hold it at the right position on a surface.

Here is what my finished product looks like, sorry about all the plurple light.

Image

Here are both in place on the tank:

Side view:
Image

Top view:
Image

Bottom view:
Image
Last edited by Rammplins on Wed Dec 13, 2017 1:04 am, edited 2 times in total.

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Re: How to build a Peltier cooler

by Wikiwakawakawee » Tue Dec 12, 2017 6:47 pm

Can you post some pics of yours please?
I don't always drink.... But when I do... I drink Rainwater.... Stay thirsty my friends.

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Re: How to build a Peltier cooler

by Rammplins » Tue Dec 12, 2017 7:12 pm

Oh yeah, no problem. I was planning on it later this afternoon anyway, by the time I got home yesterday they were already running and I didn't feel like turning it off.

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Re: How to build a Peltier cooler

by AndyTheTaco » Wed Dec 13, 2017 12:49 am

This is very useful for people like me in the tropical climate, but I'm just a kid and can't get all of materials but ill screenshot this!

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Re: How to build a Peltier cooler

by Rammplins » Wed Dec 13, 2017 1:12 am

Updated with pics, dont mind the messy wires or neon purple light. Lol

Tell them its a science project for school! In all hosety the idea came from my 8th grade invention convention.

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Re: How to build a Peltier cooler

by Rammplins » Mon Dec 18, 2017 6:41 pm

Alright, now that the guide has been out for a couple days is anyone thinking about making one? and are there any questions about putting it together or any other general questions? I am here to help.

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Re: How to build a Peltier cooler

by Hungry Plants » Sat Jan 13, 2018 1:42 am

I'm looking into building one right now. Any tips you can give after running it a bit. Is it worth the time, effort and money to build?

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Re: How to build a Peltier cooler

by Rammplins » Mon Jan 15, 2018 4:16 pm

Oh yeah, its totally worth it. I just had to switch from a 10 gal to a 20 gal tank and my cooler still manages to get it to around 54-58 at night depending on how warm it is in the room at night.

Money wise it is definitely cheaper than an air conditioner, and mine has held up with basically no problem. I did have a bad peltier from my first unit, but those are only 5$ on amazon so it wasn't a big deal. Its been going for 2 1/2 months since then and still working fine.

As far as effort goes, its actually not too bad. Once I had all the pieces I was able to put it together and have it installed on the tank in less than one evening, the longest part of the process was waiting for the thermal grease, hot glue, and silicone sealant to set.

tips:
1. don't put your fingers near the fan blades...fingers are usually much stronger.
2. superglue can be used to fix fan blades that lost the fight with your fingers.

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Re: How to build a Peltier cooler

by Hungry Plants » Tue Jan 16, 2018 1:09 am

did you put it on a timer or a thermostat?

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Re: How to build a Peltier cooler

by Rammplins » Tue Jan 16, 2018 1:50 am

I had it on a thermostat but the control only went down to 16c - 60f, so i changed it to an extra timer i had. Eventually i will get another thermostat that can bring it down a little but further

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Re: How to build a Peltier cooler

by promethean_spark » Thu Mar 01, 2018 9:15 pm

Most thermostats use a thermistor to measure the temperature (at the end of the probe). A thermistor is just a resistor that changes with temperature. A common one might be 100k at room temp. When your thermostat can't go down (or up) to the temp you want, you can add some resistance by hooking up another resistor in series, or remove some by hooking up a resistor in parallel. The termostat will then think it's regulating 70'F, but actually be regulating 50'F. Of course you will need a separate thermometer to read the real temp since the thermostat will be off - or you can just remember to subtract 20 or whatever.

-An electrical engineer who once worked at Honeywell. ;)

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Re: How to build a Peltier cooler

by aarolar » Fri Mar 02, 2018 1:52 am

This is only easy or cheap if you know where/how to source these parts. Any tips on finding them on the cheap?

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Re: How to build a Peltier cooler

by Rammplins » Fri Mar 02, 2018 2:56 pm

promethean_spark wrote: When your thermostat can't go down (or up) to the temp you want, you can add some resistance by hooking up another resistor in series, or remove some by hooking up a resistor in parallel.


Hmm, never would have thought of that. Great idea! My thermometer also has a humidity sensor on it, would the resistor also throw that off as well?

aarolar wrote:This is only easy or cheap if you know where/how to source these parts. Any tips on finding them on the cheap?


Most of the parts are under 5$ on amazon or at your local hardware/ PC store. I think the only things more than that are the CPU coolers and the power supply. The biggest problem you will have is finding a big enough power supply that is a reasonable price.

The only tips I can give to solving that is to
A) search your house for power supplies that you don't use anymore. ex. old laptop chargers, gaming console power supplies, check your junk electrics box (I don't know if everyone has that, but I have been saving all my old power supplies and random cords for years now)

B) you can buy the old xbox 360 power bricks for fairly cheap nowadays since the system is so outdated. They work perfect for this project and even come with some built in protections, just make sure you don't get the one for the xbox 360 slim, the originals have more power.

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Re: How to build a Peltier cooler

by aarolar » Fri Mar 02, 2018 3:08 pm

Rammplins wrote:
promethean_spark wrote: When your thermostat can't go down (or up) to the temp you want, you can add some resistance by hooking up another resistor in series, or remove some by hooking up a resistor in parallel.


Hmm, never would have thought of that. Great idea! My thermometer also has a humidity sensor on it, would the resistor also throw that off as well?

aarolar wrote:This is only easy or cheap if you know where/how to source these parts. Any tips on finding them on the cheap?


Most of the parts are under 5$ on amazon or at your local hardware/ PC store. I think the only things more than that are the CPU coolers and the power supply. The biggest problem you will have is finding a big enough power supply that is a reasonable price.

The only tips I can give to solving that is to
A) search your house for power supplies that you don't use anymore. ex. old laptop chargers, gaming console power supplies, check your junk electrics box (I don't know if everyone has that, but I have been saving all my old power supplies and random cords for years now)

B) you can buy the old xbox 360 power bricks for fairly cheap nowadays since the system is so outdated. They work perfect for this project and even come with some built in protections, just make sure you don't get the one for the xbox 360 slim, the originals have more power.
I have an old Xbox power supply thanks

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Re: How to build a Peltier cooler

by promethean_spark » Fri Mar 02, 2018 5:49 pm

The humidity sensor would be a separate element, so it shouldn't be messed up by hacking the thermistor. If the sensors are on a probe there should be 4 wires, you can use an ohm meter to measure the resistance between the 4 wires to figure out which pairs go to sensors, then heat it and measure again to figure out which is the thermistor. If it's a 10k NTC thermistor, adding a 300k resistor in parallel will reduce the temperature it regulates by about 10'C/20'F.


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