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Computer PSU's and Peltier elements? Answered

Hey, I have 2 158W Peltier elements, that I would like to mount to some CPU-heatsinks, and power with an old 400W PSU.

Can I "just do that"? There seams to be some caveats with how these units draw power AFAIK.

Also, does anyone have any experience with how much heat displacement is needed to not just ending up frying the unit?
Any suggestions on what heatsink to pair them with, and how strong a resistor to put on them?

I want to use them at the maximum power I can get them to run with continuously for up to 2 hours.

I have way too limited experience with electronics, and only a week to build my project, so I kind of have to go with the simplest approach here :(

Discussions

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frollard

7 years ago

The higher the voltage, the more power will be transmitted from side A to side B.

The power (heat) showing up at side B will be the sum of the power transmitted from the A side plus the power input to the electrical connections.

In order not to fry the unit, you must:
a) not exceed the maximum junction voltage, specified by the documentation
b) not exceed the maximum junction delta T - you have to dissipate the heat from the hot side or it will cook itself.

A 146 watt peltier will draw 146 watts of power from one the electrical, and according to wikipedia are about 5-10% efficient. that means you'll get 10% , about 15 watts of cooling, so the hot side will see upwards of 160-200 watts of heat. Sufficiently cool the hot side and you'll be fine.

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ELFfrollard

Answer 7 years ago

So basically just any modern CPU heatsink should do, if I just limit the voltage/highen de resistance? It's a 12V Unit, and the PSU has a 12V output, but it doesn't say if I can draw that many amps from one outlet on the unit...

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frollardELF

Answer 7 years ago

You don't need a series resistor. the peltier itself has an internal resistance that acts as a current limiter, so long as the voltage is in the appropriate range.

Don't use pwm to vary the power, because peltiers, despite being solid state, don't really like being switched on and off rapidly.

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maxshinodafrollard

Answer 6 years ago

I plug in my TEC1-12709 136.8 watt to my PC PSU (12V @ 15A... say the label) yup the peltier starting to drop down temperature for about 10 second and then the temperature start to go up.... now the cold side is just getting hotter??? is it really the CURRENT (amperage) dosen't have anytihing to do with it???

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frollardmaxshinoda

Answer 6 years ago

You NEED a heatsink on the hot side - or the heat will quickly destroy the peltier (as the heat seeps its way through the semiconductor destroying it).

If your peltier is rated for x volts, then apply x volts to it - the peltier will automatically take as much current as its ESR allows.

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maxshinodafrollard

Answer 6 years ago

I Already attached the heatsink to the peltier... the peltier is rated Vmax 15.4 and Imax 9.... is my psu is 12V15A is too much? I add a 1.5 OHM 10w wirewound resistor to cut down the current.... now the temp on the cold side is colder -10°C than the ambient temp... but still no ice!!! without the resistor the peltier cold size become hotter..... what is missing here!!

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frollardmaxshinoda

Answer 6 years ago

it might be burnt out? Really makes me think the heat is physically transferring through to the cold side

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ELFfrollard

Answer 7 years ago

So chances are, with one peltier, hooking the peltier to one of the 12V outputs, and the heatsink fan to another, should be adequate to get stable performance?

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frollardELF

Answer 7 years ago

What *exactly* are you trying to do?

Yes, hooking the wires up to suitable voltage and heatsinking the hot side it will get cold on the other side -- 'stable performance'...please tell me you're not using it to cool a CPU. These days there's no good reasons to take the risk of condensation on your pc when other cooling solutions will do.

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ELFfrollard

Answer 7 years ago

Of course not, I am trying to make a 'cold serving plate' for instant freezing and serving icecream.

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blawrence1ELF

Answer 7 years ago

I hope you received your reply earlier and checking the date, April 1st, I'm hoping you're pulling our leg.

A peltier is only capable of cooling a maximum of 40 degrees farenhiet below the room temperature on the heat sink on the hot side of the device. You'll be serving cool melted ice cream at best.