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TEC in Series or Parallel?

post #1 of 19
Thread Starter 
Hello. I have been messing with my cooler. For starters, I moved pump, to the power supply, the fan to a fan controller, hooked up a 120mm fan (yay for longer bolts) in-between the case and eliminator and my current step is to mess with the TEC themselves. Two things to mention, first the TEC are currently in series (they came that way). Second, the whole thing was powered by a Molex connector to begin with. Anyway, I removed the metal board that was stuck on with adhesive and the circuit boardbecause it was only powering the TEC which I just plugged into a Molex connector. So to my question: Would I get better performance if the 3 TEC were hooked up in parallel to the power supply or in series like they are now?

Also here are some pictures (please excuse the poor quality as the camera is missing so a phone had to suffice):

prime95 load temps and idle temps (the minimum temps):


picture of most of the setup:


a picture to show the connections of the TEC


a close up of the CPU block:


oh ya EDIT: +rep for help





Edited by digital charon - 2/4/09 at 9:00pm
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post #2 of 19
if the heat sink on the hot side is able to dispate the extra heat load when wired in parrallel. then parrallel would produce lower temps than in series. While consuming more electricty of corse.

If the hot side isn't powerful enough to keep the hot side cool then you will be worse off with the tecs connected in parrallel than in series.

Thers only one way to find out hook it up and see what happens AT LOAD

my personal opinion is the hotside heatsink wont beable to disapte the extra heat load. though you'll probably get great idle temps.

try it and post back we'd all be interested
post #3 of 19
I agree with that, I don't think the heat sinks are up to the job.

You can always try it though. You also have to consider if your power supply can supply enough power.
post #4 of 19
Hmmmmm.......

I am concerned by the replies here.

I have attempted without much luck to find out the rating of the TEC units in the eliminator.
I didn't find them so I need here to make a few general assumptions.

Currently the 3 TEC's are wired in series and since they are connected to the 12v output that means they are set to use 4v each. The current draw is obviously less than 8amps since they are molex powered. I am assuming for efficiency these TEC's are undervolted and probably of the 127 junction variety so they have a nominal voltage of 15.6 - 16v. The total power draw of the 3 TEC's is 40W so that pegs the current draw in the region of 3 amps which is generally in line with the typical current draw of a low watt rated 127 junction TEC undervolted in this manner.

So I am assuming we have 3 TEC's dropping 4v each with a current of 3 amps while wired in series.

Wired in parallel would cause something quite different.
Each TEC would drop 12v which would markedly increase the cooling of each TEC BUT the current draw would now be considerably increased as well and then because the TEC are in parallel would be multiplied 3 times !!
It would not be unreasonable for the current to double to 6amps then multiplied by 3 to 18amps.....well in excess of MOLEX connections indeed well in excess of the rating of the PSU wires. In the majority of cases with everything else you have on the 12v output it would trip the overload of the PSU....If you have a massive PSU with a hugh 12v output the wires to the TEC's will probably melt along with the molex and you have a potential fire.

Of course I might be wrong they may be specially made TEC's with totally different ratings but in that case running 12v through them will probably burn them out !
Edited by zipdogso - 2/5/09 at 3:56pm
post #5 of 19
so you need to powerthen with a external adjustable psu like a meanwell

it's a shame the chiller doesn't have a even number of tecs

you could connect each tec up to the 5 volt rail for a small increase in performace.

of you could hook them up in the 7volt fashion on a seperate pc psu
post #6 of 19
Quote:
Originally Posted by Ultrasonic2 (muffy) View Post
so you need to powerthen with a external adjustable psu like a meanwell.
Absolutely...

Shame one can't find the proper rating for the TEC...that would help heaps.
For quite a few reasons though I don't think my assumptions are too far off and it wouldn't surprise me greatly if these arent 16v 8.5A units with a Qcmax of about 80w.

Quote:
Originally Posted by Ultrasonic2 (muffy) View Post
it's a shame the chiller doesn't have a even number of tecs
Yes ....four would of been nice;
Edited by zipdogso - 2/5/09 at 6:10pm
post #7 of 19
i think your estimations are about right too .. do you have a spear psu to use for testing ?
post #8 of 19
i think 5 volts could work
post #9 of 19
Quote:
Originally Posted by Ultrasonic2 (muffy) View Post
i think 5 volts could work
9amps would be pushing the molex a bit...for safety I wouldn't go more 7-8 and the wires would get darn hot.
Would you really want to try too see if I'm right ?

EDIT actually no...5v would mean 3 in parallel in the 10 amp range.
Mind you if the hotside cooling is not good and the temp delta is high I could be overstating the amps and 5v might just work

could be one for testing if you don't mind potential damage.
Edited by zipdogso - 2/5/09 at 6:35pm
post #10 of 19
Thread Starter 
An update:

I got them hooked up in parallel. Plugged them in, hit the power button and it flashed on for a second then went off. So I unplugged one TEC and tried again. This time it got to the windows logon screen where I type in my password but right after doing so, it shut off. So I tried with one TEC. This time it booted up, I logged in and opened real temp to find my temps around 28-32c.

More notes:
1. The ~40watt number includes the pump and 92mm fan (also a little LED but that doesn’t do anything really).
2. Link to my PSU: http://www.newegg.com/Product/Produc...82E16817152035

-------

About an hour after being distracted by the thing I was writing the post about:

I got a PSU tester and a 450 watt PSU that I had lying around (was powering an athlon 64 but that comp needs a new Northbridge heat sink so . I plugged two of the TEC into the 450watt and one into my normal 630 watt.

Heat is definitely a problem but that isn’t the end of it. The wires are warm, not ouch if you touch them warm but I know there is current running through them (not the PSU wires but the wires in-between the molex connector and the wires that came with the TEC. The heat sink was quite hot even idling so I did not try to put load on the processor (the heatsink felt to be about the same temperature as when it was under load before. Additionally I had to turn it off because it was soon apparent that the small blue reservoirs on the eliminator were starting to accumulate condensation. That hasn’t happened before to my knowledge so its probably a sign that the liquid is colder however I now am left with the problem that the temperatures were exactly the same as before (I do mean exactly. It used to idle at 18 18 23 18 with the first core dropping down to 17 for an instant. It would sit at that temperature which I assumed was because the little temp monitors didn’t like to go below that. So now with the coolers condensing the surrounding liquid, the temps are 18 18 23 18. Weird.)

1.Any ideas on additional cooling?
2.Also, If the limiting factor is the heat-sink’s ability to dissipate heat, what would happen if I hooked each Tec up to its own cooler (something like a arctic freezer 7 pro)?
3.Would it be beneficial in your opinions to hook two of the TEC in series and one parallel to them?

-----------------------------------

yet another update within the same post

NEVER EVER EVER leave the 2nd psu on when the main comp goes off! These things are insanely hot now! like there is a big bulge in the tubing where the heat allowed it to expand and it was filled halfway with gas and half with darker than normal liquid in the bottom of this buldge. I must give coolit lots of credit on sealing these things though. no leak :S CPU block never got hot (pump was hooked up to the normal power supply) so I probably just killed this adventure...

here is a pic of a visible result of the heat (it shrunk down alot before I took this picture):

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