Quote:
Originally Posted by luka
Brendan, did I understand correctly that your hot and cold heatsinks are joined by metal? That will transfer the heat. Another thing to consider is if the cold side is getting warmed up by the fan from the hot side?
Did you use any heat transfer compound?
How big is the heat sink? If it is large, you could try running the thing at full power without the fan and KEEP AN EYE ON THE HEATSINK TEMPERATURE. Don't let it get too hot or you will kill the TEC. And don't do this without the thermal compound.
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Hi Luka...its just a metal spring clip used in many older computer HSFs to clamp the HSF down. Contact surface of this is small very small but yes it will loose some efficiency between Hot/cold sides. This is a "rough" test just to find a sweet spot and if the TEC is suitable.
I'm still fiddling with TEC voltages. There does appear to be a sweet spot of efficiency for the TEC. I am getting better cooling using ~7V compared to 5V or 13V.
Yes I'm using thermal grease. I'll fiddle with HSF fans but I'll try to find the optimum TEC voltage first as I think this is the key.
Brendan
edit:
Ahh getting better results now:
TEC @7.08V, TEC I draw 1.54A, cold side @ -4.2ēC/hot side HSF 22.4ēC. HSF fan @12V DC. So its working better much better
TEC @7.42V, TEC I draw 1.6A, cold side @ -5VēC/hot side HSF 22.4ēC. HSF fan @12V DC. So its working even better and deeper cooling.
Repeating above voltages but throttling fan @same as TEC voltage:
TEC @7.1V, TEC I draw 1.52A, cold side @ -4.1ēC/hot side HSF 24.1ēC. HSF fan @7.1V DC. So throttling allowing hot side fan to increase this a few degrees doesn't appear to help cooling capacity.
TEC @7.43V, TEC I draw 1.6A, cold side @ -4.7ēC/hot side HSF 24.6ēC. HSF fan @7.43V DC.
Now I'm at a small wall!
My variable computer PSU can only vary up/down a small range as I modified under/over voltage trip points. So I only have so much range in adjustment. Using the 5V rail I can get from 4.5V to 7.42V and the 12V rail from 11V to 18V. So I've run out of adjustment to run the TEC. I need and 8V and 9V source. Sigh... it never ends. Ireally need to try these voltages. Wonder if I can hook between 3.3V rail and 12V rail?