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Thread: TEC undervolting charts

  1. #1
    beefin' it up!
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    TEC undervolting charts

    Attention: This post is not accurate, but it will hopefully be revised in the future to resemble some form of factuality.


    Since peltier cooling power is nonlinear, calculating cooling power at voltages other than VMax can be difficult. To make life easy, I've assembled a chart of cooling powers for some standard TECs using the formula... snipped
    YAY REWRITE! OK, much thanks to shadowing on this one :-). the new formula is P=(I^2)R. P = wattage, I = amperage, R = resistance.
    First, I derive the resistance from the manufacturer-provided numbers. then, using these, i make I x and get the wattages for each amp.
    OK, since I was dead-tired when I was updating this whole chart last night, I didn't bother to give you guys the real formula used (derived from P=(I^2)R), so here it is (as it appears on my TI-83+):
    \y1=(((x/16.1*8.0))^2)*(80/(8.0^2))
    thats how it would look for the 80watt TEC listed below.
    here is the article that, after reading through it several times late last night, yielded the equation.
    Much to my surprise, my amperage draw approximations were pretty much dead on; it was the wattages that made no sense at all

    Keep in mind, these numbers are "rough guidelines" at best! Don't follow them too closely. I'd like to update this sometime soon with numbers that I'm more confident about, but I don't see that happening any time soon.

    80 watt / 16.1 VMax / 8.0 IMax
    5 volts: 5.7 watts; 2.48 amps
    6 volts: 8.9 watts; 2.98 amps
    7 volts: 12.8 watts; 3.47 amps
    8 volts: 17.4 watts; 3.97 amps
    9 volts: 22.8 watts; 4.47 amps
    10 volts: 28.8 watts; 4.96 amps
    11 volts: 35.6 watts; 5.46 amps
    12 volts: 43.0 watts; 5.96 amps
    13 volts: 51.2 watts; 6.45 amps
    14 volts: 60.1 watts; 6.95 amps
    15 volts: 69.7 watts; 7.45 amps
    16 volts: 80 watts; 7.95 amps

    120 watts / 24.6 VMax / 7.9 IMax
    5 volts: 3.5 watts; 1.60 amps
    6 volts: 5.5 watts; 1.92 amps
    7 volts: 8.0 watts; 2.24 amps
    8 volts: 10.8 watts; 2.56 amps
    9 volts: 14.1 watts; 2.89 amps
    10 volts: 17.9 watts; 3.21 amps
    11 volts: 22.1 watts; 3.53 amps
    12 volts: 26.7 watts; 3.85 amps
    13 volts: 31.0 watts; 4.17 amps
    14 volts: 36.4 watts; 4.49 amps
    15 volts: 42.2 watts; 4.81 amps
    16 volts: 48.5 watts; 5.13 amps
    17 volts: 55.2 watts; 5.45 amps
    18 volts: 62.3 watts; 5.78 amps
    19 volts: 69.8 watts; 6.1 amps
    20 volts: 77.8 watts; 6.42 amps
    21 volts: 86.2 watts; 6.74 amps
    22 volts: 95.0 watts; 7.06 amps
    23 volts: 104.3 watts; 7.38 amps
    24 volts: 114.0 watts; 7.70 amps

    169 watt / 16.4 VMax / 16.1 IMax
    5 volts: 15.7 watts; 4.90 amps
    6 volts: 22.6 watts; 5.89 amps
    7 volts: 30.8 watts; 6.87 amps
    8 volts: 40.2 watts; 7.85 amps
    9 volts: 50.9 watts; 8.83 amps
    10 volts: 62.8 watts; 9.81 amps
    11 volts: 76.0 watts; 10.79 amps
    12 volts: 90.5 watts; 11.78 amps
    13 volts: 106.2 watts; 12.76 amps
    14 volts: 123.2 watts; 13.74 amps
    15 volts: 141.4 watts; 14.72 amps
    16 volts: 160.9 watts; 15.70 amps

    172 watt / 24.6 VMax / 11.3 IMax (got the numbers from silverprop)
    5 volts: 7.1 watts; 2.3 amps
    6 volts: 10.2 watts; 2.8 amps
    7 volts: 13.9 watts; 3.2 amps
    8 volts: 18.2 watts; 3.7 amps
    9 volts: 23.0 watts; 4.1 amps
    10 volts: 28.4 watts; 4.6 amps
    11 volts: 34.4 watts; 5.1 amps
    12 volts: 40.9 watts; 5.5 amps
    13 volts: 48.0 watts; 6.0 amps
    14 volts: 55.7 watts; 6.4 amps
    15 volts: 64.0 watts; 6.9 amps
    16 volts: 72.8 watts; 7.3 amps
    17 volts: 82.1 watts; 7.8 amps
    18 volts: 92.1 watts; 8.3 amps
    19 volts: 102.6 watts; 8.7 amps
    20 volts: 113.7 watts; 9.2 amps
    21 volts: 125.3 watts; 9.6 amps
    22 volts: 137.6 watts; 10.1 amps
    23 volts: 150.4 watts; 10.6 amps
    24 volts: 163.7 watts; 11.0 amps

    226 watt / 15.2 VMax / 24 IMax
    5 volts: 24.5 watts; 7.89 amps
    6 volts: 35.2 watts; 9.47 amps
    7 volts: 47.9 watts; 11.05 amps
    8 volts: 62.6 watts; 12.63 amps
    9 volts: 79.2 watts; 14.21 amps
    10 volts: 97.8 watts; 15.78 amps
    11 volts: 118.4 watts; 17.36 amps
    12 volts: 140.9 watts; 18.94 amps
    13 volts: 165.3 watts; 20.52 amps
    14 volts: 191.7 watts; 22.10 amps
    15 volts: 220.1 watts; 23.68 amps

    320 watt / 14 VMax / 26 IMax (these numbers were given to me by NoL, so if they're wrong, yell at him, not me)
    5 volts: 40.8 watts; 9.3 amps
    6 volts: 58.7 watts; 11.1 amps
    7 volts: 80 watts; 13 amps
    8 volts: 104.5 watts; 14.9 amps
    9 volts: 132.2 watts; 16.7 amps
    10 volts: 163.3 watts; 18.6 amps
    11 volts: 197.6 watts; 20.4 amps
    12 volts: 235.1 watts; 22.3 amps
    13 volts: 275.9 watts; 24.1 amps
    14 volts: 320 watts; 26 amps

    OK, now, because wintsch labs gives conflicting information on this bad boy, theres 2 charts. I don't know which one is right, because wintsch labs is wierd. Here's the 32.8 IMax one; the second is the 25 IMax one.
    437 watt / 26.7 VMax / 32.8 IMax
    5 volts: 15.3 watts; 6.14 amps
    6 volts: 22.1 watts; 7.37 amps
    7 volts: 30.0 watts; 8.59 amps
    8 volts: 39.2 watts; 9.82 amps
    9 volts: 49.7 watts; 11.05 amps
    10 volts: 61.3 watts; 12.28 amps
    11 volts: 74.2 watts; 13.51 amps
    12 volts: 88.3 watts; 14.74 amps
    13 volts: 103.6 watts; 15.97 amps
    14 volts: 120.2 watts; 17.19 amps
    15 volts: 137.9 watts; 18.42 amps
    16 volts: 156.9 watts; 19.65 amps
    17 volts: 177.2 watts; 20.88 amps
    18 volts: 198.6 watts; 22.11 amps
    19 volts: 221.3 watts; 23.34 amps
    20 volts: 245.2 watts; 24.56 amps
    21 volts: 270.3 watts; 25.79 amps
    22 volts: 296.7 watts; 27.02 amps
    23 volts: 324.3 watts; 28.25 amps
    24 volts: 353.1 watts; 29.48 amps
    25 volts: 383.1 watts; 30.71 amps
    26 volts: 414.4 watts; 31.94 amps

    437 watt / 24 VMax / 25 IMax
    5 volts: 19.0 watts; 5.2 amps
    6 volts: 27.3 watts; 6.2 amps
    7 volts: 37.2 watts; 7.3 amps
    8 volts: 48.6 watts; 8.3 amps
    9 volts: 61.5 watts; 9.4 amps
    10 volts: 75.9 watts; 10.4 amps
    11 volts: 91.8 watts; 11.5 amps
    12 volts: 109.3 watts; 12.5 amps
    13 volts: 128.2 watts; 13.5 amps
    14 volts: 148.7 watts; 14.6 amps
    15 volts: 170.7 watts; 15.6 amps
    16 volts: 194.2 watts; 16.7 amps
    17 volts: 219.3 watts; 17.7 amps
    18 volts: 245.8 watts; 18.8 amps
    19 volts: 273.9 watts; 19.8 amps
    20 volts: 303.5 watts; 20.8 amps
    21 volts: 334.6 watts; 21.9 amps
    22 volts: 367.2 watts; 22.9 amps
    23 volts: 401.3 watts; 24.0 amps
    24 volts: 437 watts; 25 amps


    I hope this chart is useful for somebody out there. If my equation for calculating these values is flawed in any way, please let me know! All of these TECs (except the 320 watt) are units sold either by dangerden or by frozenCPU and all numbers are taken from their specs.
    Last edited by Bloody_Sorcerer; 05-03-2008 at 05:24 PM.

  2. #2
    The Blue Dolphin
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    Very nice and helpfull

    Can you include the power the TEC draws at certain volts? And maybe a TEC reated at 226.1w at 12v? (if you have the time for it)

    Thanks in advance
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  3. #3
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    Problem is that the power the TEC draws depends on the temperature differential over it...

    So the hotter your waterblock then less current it will draw (lower DT) but worse temps.

    Vice versa, reduce your water temp (and increase DT) then the TEC will draw more power.

  4. #4
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    you god that really helps when you cba to do the calculations... or find tec specs to do them
    do you have a table for a 320W 15V pelt?


  5. #5
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    updated with amperage approximations. anyone have the right info for the DD 172 watt pelt? their site just clones over the 120 watt pelt's specs.
    I'll add the 320 watt pelt soon; got a link to a supplier? I can't seem to find any very easily.

  6. #6
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    Thermal Enterprises model CP1-12726

    IDK if they have a website, if you email the guy named thermalenterprises on ebay he may be able to get the values for you. I am very interested in using one of these @5v.

    Good to see im not the only one using big pelts at diff voltages

    EDIT:

    Dividing amperage by the voltage you are running at is not a good way to predict amperage......How are you calculating that?

    Just spot checking one example with the kryotherm software, you will be drawing 3.24A from the 80w unit at 5v. Would be interesting to see what is causeing this.

    Qc seems to be about right though.
    Last edited by ls7corvete; 07-06-2005 at 12:51 PM.

  7. #7
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    got a 320 here too, been looking around for a 5-10v variable PSU for it..
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  8. #8
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    Quote Originally Posted by ls7corvete
    Thermal Enterprises model CP1-12726

    IDK if they have a website, if you email the guy named thermalenterprises on ebay he may be able to get the values for you. I am very interested in using one of these @5v.

    Good to see im not the only one using big pelts at diff voltages

    EDIT:

    Dividing amperage by the voltage you are running at is not a good way to predict amperage......How are you calculating that?

    Just spot checking one example with the kryotherm software, you will be drawing 3.24A from the 80w unit at 5v. Would be interesting to see what is causeing this.

    Qc seems to be about right though.
    for amperage i was just doing (voltage)/VMax*IMax.The results do seem kinda fishy though.

  9. #9
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    yea they arent matching with kryotherm so I would say that they are questionable.

  10. #10
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    Very Nice Info you got there. Can anyone verify this to make sure all the info is correct and no issues are to be had anywhere.

    I ask as I want to make this a sticky, but most certainly want to make sure all the info is correct and there are no annotations that need to be added before I do.

  11. #11
    The Blue Dolphin
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    The Imax is a bit wrong I think.

    For example the Imax of the 80W pelt at 5v is 2.48A. Then it uses 12.4w at 5v? that must be wrong. I don't think your way to calculate the Imax is correct.
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  12. #12
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    Quote Originally Posted by Bloody_Sorcerer
    ..................

    437 watt / 26.7 VMax / 32.8 IMax
    5 volts: 148.3 watts; 6.14 amps
    6 volts: 174.3 watts; 7.37 amps
    7 volts: 199.1 watts; 8.59 amps
    8 volts: 222.6 watts; 9.82 amps
    9 volts: 244.9 watts; 11.05 amps
    10 volts: 266.0 watts; 12.28 amps
    11 volts: 285.9 watts; 13.51 amps
    12 volts: 304.5 watts; 14.74 amps
    13 volts: 321.9 watts; 15.97 amps
    14 volts: 338.1 watts; 17.19 amps
    15 volts: 353.0 watts; 18.42 amps
    16 volts: 366.8 watts; 19.65 amps
    17 volts: 379.3 watts; 20.88 amps
    18 volts: 390.6 watts; 22.11 amps
    19 volts: 400.6 watts; 23.34 amps
    20 volts: 409.4 watts; 24.56 amps
    21 volts: 417.0 watts; 25.79 amps
    22 volts: 423.4 watts; 27.02 amps
    23 volts: 428.6 watts; 28.25 amps
    24 volts: 432.5 watts; 29.48 amps
    25 volts: 435.2 watts; 30.71 amps
    26 volts: 436.7 watts; 31.94 amps
    ............................................
    Impressed with accuracy of 437 table. I'm using a 437W at 19.9V. Current draw is 24.4A.


    EDITED for brevity
    Last edited by MaxxxRacer; 07-19-2005 at 09:01 AM.

  13. #13
    beefin' it up!
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    I'm fairly confident that my wattage numbers are correct, but obviously something is wrong with the amperages. Currently, I'm looking for a better equation to calculate them. Still missing IMaxes for 320watt and 172watt TECs.

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    for the 320, its 26 amps.

  15. #15
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    gah, these amperages are driving me crazy! I had been trying a method in which i took the % efficiency of the peltier (watts drawn / watts cooled) and multiplied that by the new watts cooled and then divided by the new voltage, which seemed to work mostly, until i tried it on the 437watt tec,where it went absolutely bonkers, suggesting that it draws 50-plus amps at 12volts, something i highly doubt. I'm also starting to think that it's amperage figure is totally wrong, too. I doubt that a 437watt tec draws 875 watts at VMax.

  16. #16
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    they lose efficiency as voltage increases.. it might be near to that.
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    Thanks Sorcerer!

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    bloody when ur 98% confident its all right shoot me a PM and I will sticky it. until then its a WIP.

  19. #19
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    you can try kryotherm calculator for the amps.

    I think amperage is gonna vary too much to make a chart.

  20. #20
    beefin' it up!
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    I'm declaring this done. Amperages are all approximate. huge thanks again to shadowing :-)

  21. #21
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    What about 350 watt peltiers? But great stuff man. Thanks a bundle.


    If you have a cooling question or concern feel free to contact me.

  22. #22
    beefin' it up!
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    w00t! updated! finally got numbers for 172 watt TECs (from silverprop's e-store) and used numbers from NoL (who got them from eBay) for 320 watt TECs, so those could be wrong :-P
    this was supposed to get updated last night, but i left my TI-83+ in school...
    if anyone wants them, I'll but the exact equations i used for each TEC in.

  23. #23
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    where can i find a 320w pelt in the usa

  24. #24
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    Ebay thermoelectric enterprises
    AMD Sempron 3000+ socket754 @ 2.4 ghz with peltier chilled watercooling.

  25. #25
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    When were the values changed?

    The wattage values are completley wrong, they need to be changed, they seemed pretty close before.

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