TEC Help

[gtr_stitch]

So I just received a couple of peltier modules and am having a bit of trouble. First off, I'm not sure how to power them. I tried a 9V. Tried an ac adapter rated for 9v and 100ma (which my multimeter read 14v, so that may or may not be an issue) and nothin'. Here are the specs
operates at 0-15.2v dc 0-9A
max power consumption 138.6 watts
Any idea what I'm doing wrong? Any idea how I should power this? Any feedback would be awesome!

 

[ronv]

You need a power supply that can supply quite a bit of current. A 12 volt PC supply would do it. Make sure to use a heat sink on the hot side or it will kill it.

 

[Sceadwian]

9 volts at 100ma is .9watts.... The max power consumption you listed is 138watts... There is definitely a problem! You could in theory measure the temperature of the cold junction and get something very slightly less than ambient.

You need a 12V supply capable of VERY if not far past 9amps (for overhead). Ideally you would feed it with a constant current 9amp supply, but that's at max...

 

[gtr_stitch]

Thanks guys!

One last little tid-bit before I depart...
I plan to use my peltier to cool my cpu (seems to be running hot lately). It's TDP is 35W. Now, I know 35W is not exact, and I'm pretty confident my cpu is running a little above that. I've been doing some research on, well, whatever I could find.
Earlier this evening, I managed to find an AC Adapter rated for 12VDC and 1A. I made some mods and hooked everything up, and the cold side got cold fairly quick, which says to me that 1A was enough to get it cold.
Given that result, could I run my TEC off of the 5V rail on the PSU and still achieve a decent cool-down? I'm not looking to freeze anything (at least not in my PC). Or would the 5V rail not have enough amperage to run it? And if I do have to use the 12V rail, do you think I could fashion up a circuit to bring the amperage down enough to avoid frost, but still maintain something at or barely above ambient?
I really appreciate the help, guys!

 

[cr0sh]

I plan to use my peltier to cool my cpu (seems to be running hot lately). It's TDP is 35W. Now, I know 35W is not exact, and I'm pretty confident my cpu is running a little above that. I've been doing some research on, well, whatever I could find.

Have you checked to see what temperature your CPU is actually running at, and comparing that to what it is rated to run at? In other words, are you sure that it is getting too hot?

Maybe it did rise in temperature, but I would think that would be due to either:

1) poor contact between the heatsink and the CPU
2) something wrong with the fan
3) fan or heatsink clogged up with dust

My first thought would not be to go out and purchase a TEC, especially if it had been running fine all along without one.

Instead, I would probably pull the heatsink/fan and blow it out with canned air (don't spin up the fan to high speeds with the air or you can make the bearing fail). Then I would test it with a 12 VDC supply to make sure the fan was running well. I'd re-install it (with new heatsink grease or thermal pad, after cleaning off the CPU of any old grease/pad), and verify that the RPM of the fan was proper.

If that didn't work, Id then go out and purchase a new heatsink/fan combo, clean off the CPU properly using some rubbing alcohol and swabs, then applying the paste or thermal pad or whatnot and remounting the heatsink. Done properly, you'd probably see the temperature come right back down to where it should.

I'd also take the time, while I had the case apart, to blow out any other dust in the system (especially from any fans and heatsinks, including the power supply). That's really all it should take.

Instead, you are looking at doing an experiment while increasing the amount of power your system draws in total, with possibly little gain overall. Not only that, but should you cool things down too much, you might see an increase in condensation, and possibly causing shorts or such (all depending on the humidity and other environmental factors).

 

[gtr_stitch]

In all honesty, it was never planned to use my TEC for this purpose. I recently acquired two with the intent of using one for something...practical. Cooling my CPU was just the first idea that came to mind. At any rate, I do appreciate the feedback! I am, however, most certain there is a buildup of dust, so maybe that will solve the CPU issue to some extent. At the moment, according to SpeedFan, my CPU is sitting at 39C.
But as I said, I never purchased my TECs to put them in my computer. It's another aspect of electronics and circuitry that I am learning about. And as well, quite fun.
Again, I do appreciate the feedback as it all has been most helpful!

 

[Sceadwian]

Given that result, could I run my TEC off of the 5V rail on the PSU and still achieve a decent cool-down?

NO All TEC modules I have ever seen are optimized for 16volts and will run fine on 12, if you run it on any lower voltage you're throwing your money away, problem is if you run them optimally you WILL have interface issues with the cold side causing condensation from ambient air.

cr0sh posts is most relevent, CPU's don't simply heat up more over time.. What's more than likley happening is a degradation of the thermal grease on the CPU/heatsink, or the fan or the heatsink itself.

If the heatsink is clean, no dust, the fan runs at normal speeds with no dust and the thermal grease was cleaned off and redone you should be fine.

This just recently happened to my sisters computer where she started to observe random crashes, and then it up and one day died. I diagnosed a bad hard drive from age (replaced) and when I did I took a look at the chip/heatsink interface, the grease had dried from constant heating over a couple years to a brick hard crust that is useless, the machine runs stable and cool now.

Take the original heatsink, clean it well with alcohol to remove thermal grease residue, do the same to the CPU, buy yourself some thermal paste put a small dab on both the chip and the heatsink and scrape the excess off (more is not better you only want to fill the air gaps with as thin a layer as you can), place the heatsink back on the cpu carefully pressing firmly but carefully and twisting it as you go before sealing it back with the clips and you should see a dramatic drop in CPU temperature.

My system is actually about due for this treatment. I do a once yearly brush+vacuum of the internal components and re-do the heatsink interface every two years.

 

[gtr_stitch]

I appreciate the info, guys.

 

[ronv]

On the surface TEC's sound perfect for CPU cooling, but in real life not so good. They are really not very efficient. In other words you may need to put in 150 watts to move 30 watts from the cold side to the hot side. Once you have done that what do you do with the extra heat. You need to get it outside the cabinet or it heats up everything else. So you end up with a bigger heatsink and fan outside the cabinet... Well you get the idea.

 

[Sceadwian]

On the surface TEC's sound perfect for CPU cooling, but in real life not so good

On what basis do you make this statement?! A well engineered TEC module and airflow on a high performance processor can allow it to run substantially over it's rated clock speed safely. Efficiency doesn't mean anything when you consider that it can cool BELLOW ambient, the only thing better than a TEC module would be forced liquid cooling which is actually probably better than a TEC module, I've seen totally sealed units which can be used with TEC's to further increase the possible cooling to the chip.

The extra heat created by the TEC module and air flow design of the case are absolutly critical and should not be overlooked, nor should the failure of someone taking these into account give TEC modules a bad name (which they do) the best technology on earth not used properly is a waste of time and money.

 

[gtr_stitch]

So, I've been doing some research and so far the general consensus is that a PSU may not be a great idea to power a TEC module. I figured I would pose this question to guys I trust: is that right? I hear about using tecs to cool overclocked CPUs, and even in conjunction with liquid cooling, yet, I read that a psu, even a dedicated one, may not be smart. what's with all the back and forth? I would like to know from people who know what they're talking about. I'm set to purchase a psu not for just the tec, but also as a power supply for my workbench, as I enjoy getting use out of my stuff for more than one thing. So...any thoughts before I hit 'buy'? Would it even be worth it?

 

[ronv]

Give this a good read. Of course it can be done, but it is not as easy or as cool as most envision.

http://www.heatsink-guide.com/peltier.htm

 

[gtr_stitch]

Wow! Thanks Ron! I'm kinda just skimming it at the moment, but this article is fantastic!