Written 2016-01-03

Tags:Peltier Woodsman Fridge 


My friend Jeff had a fridge. It broke. Now I have a broken fridge.


This is a peltier fridge. Meaning it uses the thermoelectric effect to to cool. We will get into driving Peltier junctions later.

Fridge Design Overview

The basic design is an insulated box, with one or more cooling units (this one has two), driven by a control board. The cooling units consist of a small heatsink and fan on the inside of the box, a large heatsink and fan on the outside of the box, and a Peltier junction between them. The control board converts utility power, commonly at 100 to 240 volts AC, to DC voltage to drive the Peltiers.


Peltier fridges can fail in a few different ways.
  • Fans can jam with dust - this prevents removing heat from the Peltier junctions
  • Peltier junctions can fail, commonly from thermal stress
  • Control board can wear out
In this case, the control board produces 12V for the fans, but no longer converts the 12V down to drive the Peltiers, so the control board is bad.


A new control board is required. I'll likely be moving to a simple Bang-Bang controller, although more advanced and efficient designs are available.