Hi, there. Welcome back!

In recent years, smartphone technology has advanced exponentially, packing so much power in very tiny footprint that leads to one problem, excessive heat. Physical limitation on a smartphone limits the maximum heat that can be dissipated efficiently, which is on the low side compared to other devices. I sometimes play video games on my phone, which are resource hungry. My phone then gets too hot, which makes gameplay laggy. Also, my hand gets sweaty which double the trouble! Luckily, such product does exist on the market such as that smartphone cooling pad which even includes 5V output for your device! Also, there are many DIYs projects showing how to make one yourself! But, I wasn't satisfied enough. It's just a fan, what's so fun about that? I want something different, something fancy, something that probably has never done before. An ultimate peltier cooled smartphone!

Step 1: The Materials and Tools

Main materials:

1X 12703 12V 3A 30*30mm thermoelectric cooler module
1X Small heatsink with 12V fan
1X Tripod phone holder
1X 45*50mm 1mm thick aluminium sheet
1X 45*50mm 1mm silicone thermal pad
2X generic 3A switching step-down converter
1X DC jack

Consumables:

Heatshrinks
Solder
Thermal glue (not thermal paste)
Wires
Double-sided tape
CA glue

Tools:

Soldering iron
Unused card
Scissors
Flat head screwdriver
File

Step 2: Fixing Peltier With Thermal Glue

First, apply a thin layer of thermal glue evenly and place the peltier module on top. Apply a bit of pressure to make sure good contact between the heatsink and the peltier module. Don't rush it, wait until the glue sets.

Step 3: Modifying the Holder

The grooves on the inner part of the holder have to go in order to fit the peltier module. Use a file to file the groove flush.

Step 4: Fixing the Holder to the Heatsink

Sand both side of the surface that will touch each other and put just enough CA glue to the surface and press hardly to ensure good contact.

Step 5: Fixing the Aluminium Plate to the Peltier

Apply a thin layer of thermal glue to the peltier evenly. Place the aluminium plate on top and press it just enough to make sure good contact between the peltier and the plate.

Step 6: Soldering the 3A Stepdown #1

Set the output of the converter to 5V first before soldering anything else. Stick the stepdown with double-sided tape. Beware of the conductive heatsink below. Solder the output of the module to the peltier according to the polarity.

Step 7: Soldering the 3A Stepdown #2

Set the output to 13V first. Solder the output of the module to the fan.

Step 8: Wiring the Input

Connect both stepdowns on parallel with some wires. Put DC connector on the other end. Zip tie the wire so it won''t stress the solder joint.

Step 9: Add Thermal Pad

Last, put the thermal pad to the aluminium plate and done! You can apply some thermal glue beforehand for more permanent solution but I like mine to be removable. The thermal pad really helps with the heat transfer. You can tweak the two stepdowns to get the maximum cooling power with minimum noise. Mine happens to have the peltier on 8V and fan on 13.5V due to the power of the peltier used here.

Step 10: Afterthought

My peltier phone cooler does work very well, probably too well. The peltier I used here (12V 3A) is actually too powerful for this application. Even at 8V, the cooling power is enough to make my phone condense within minutes. I'd suggest using another peltier module such as TES1-4903 5V 3A peltier module with smaller heatsink. Don't let the size fool you like it did to me, they still pack enough power to cool down your phone. I'm going to make another one based on this 5V peltier and I'll do an update on it.