Peltier Module (TEC)
Thermoelectric Cooler
A solid-state heat pump: pass DC through a sandwich of semiconductor junctions and one face gets cold while the other gets hot (the Peltier effect). No moving parts, tiny size — but power-hungry and utterly dependent on hot-side cooling.
What it looks like
Peltier Module (TEC)
A typical thermoelectric cooler — exact shape, colour and markings vary between manufacturers.
Types & variants
Key specs
Imax / Vmax
A / VTEC1-12706: 6 A, 15.4 V max. Run at 50–70% of Imax for best practical efficiency.
Qmax
WMaximum heat pumped at ΔT = 0. Real pumping capacity falls to zero as ΔT approaches ΔTmax.
ΔTmax
°CMaximum face-to-face temperature difference (~65–70 °C single stage) — achieved only at zero heat load.
COP
—Heat pumped ÷ electrical power — typically well below 1. The hot side must shed load + input power.
Size
mm40×40×3.8 mm is the ubiquitous format.
Laws that govern it
The device is named for its law: current through the junction pumps heat from one face to the other, and reversing the current reverses the direction.
The same module run backwards — heat one side and it generates a voltage — which is how thermoelectric generators work.
- Joule's law of heatingH = I² × R × t
The catch: the module's own I²R heating fights the pumping, so past an optimum current you cool less, not more.
- Watt's lawP = V × I = I²R = V²/R
Total heat to reject on the hot side is the heat pumped plus the electrical power in, which is why the hot-side heatsink must be oversized.
Each law is stated in full — with its diagram, variables and worked meaning — on the electrical laws page.
Markings
Model printed on the ceramic face: TEC1-12706 = single stage, 127 couples, 6 A. Red wire +, black − ; with red to +, the printed face is usually the hot side (verify by touch at low current).
Standard values
TEC1-12703/12705/12706/12710/12715 (3–15 A at ~12 V), 20×20 mm minis, and 12706 remains the hobby default.
How to choose
1) Compute the real heat load, then pick Qmax ≈ 2× that. 2) Budget hot-side cooling for load + electrical input (a 60 W module can dump 120 W+) — a big sink AND fan is mandatory. 3) Drive from smooth DC (ripple degrades pumping); PWM only through an LC filter. 4) For temperature control use a PID driver, not on/off switching — thermal cycling cracks modules. 5) Below-ambient cooling means condensation: plan insulation and drainage.
Pinout & package
Two wires. Sandwich mounting: cold plate — TEC — heatsink, thin thermal paste both sides, even clamping pressure with spring screws. Reversing polarity swaps hot and cold faces.
Example circuits
- Mini fridge: 12706 + big hot-side sink/fan + cold plate in an insulated box
- Dew-point camera cooler for astrophotography with PID control
- CPU 'chiller' demo (mind the condensation!)
- TEG: camp-stove heat + heatsink generating ~1–5 W to charge a phone
Common failures
Cracked internal junctions from thermal cycling or uneven clamping (open circuit or lost capacity), overheating death when the hot-side fan fails (module cooks itself within a minute), moisture corrosion at the edges, and 'it heats but barely cools' from inadequate hot-side sinking.
How to test
Resistance check: a 12706 reads ~1.8–2.5 Ω (open = cracked). Function: brief 1–2 A test — faces should split hot/cold within seconds. Seebeck test: hold hot face on a warm cup, measure millivolts generated across the leads.
Substitutes
Same footprint and similar Imax swaps directly. For real refrigeration loads, compressor systems are far more efficient; TECs win on size, silence, precision and no moving parts.