This is a 12706 module. Running in a 15 minute "on", 2 minute "off" cycle for about 3 days. I have used it another maybe 4 days max since I purchased it. So definitely nowhere near its rated life cycles.
Using 12V power supply. Clean. Pulling about 4A. Proper heat sinks on both sides. Good stable temperature differential for 3 days and then suddenly, temperature differential went away. Hot side sink was around 105°F. Cold side sink would form ice if I let it run straight without the 2 minute "off" cycles. I didn't want ice. Sorry, didn't measure temperature here, but air temperature on cold side was 45°F, when room temperature was around 75°F.
I do have to confess that I missed putting foam around it and it did have condensation and some ice around it.
My only thought is that somehow some water got in through the original RTV silicone coated heavily around the edges (as purchased, not applied by me), causing short circuit inside the module? I didn't see any cracks in the silicone before I opened this module up. It was super tight.
Any other thoughts? What else causes Peltier premature failures like this?
Thank you!
Best Answer
Peltiers are difficult, and that cycling may have not been right. When you say 'about', without knowing the curves and how it's set up, that might have been too much- 48watts from your numbers, meaning a passive heatsink needed about 480 sq inches.
Also appears to have shorted between first row/column and second.
I always re-potted mine with blue RTV (electronic) after sealing it to a surface.