(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.
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)
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$, but don't. I have found that the quality will be much higher if your bulid it yourself, plus most of the pre-built peltier coolers on the market don't have fans/ heatsinks that cool down the hot side enough for what we need to use them for or are way overpriced for what they are.
Here are my materials: comes out to around 50$
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
-Soldering gun/ wire crimper/ screw on wire caps
-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.
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
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: 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
5. Connect the remaining positive ends from the cooler to the PSU, then do the same for negative wires.
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.
Here are both in place on the tank: