Thermotek Chillers Exposed! (TEC Question)

[300EVIL]

...yes, but you must watch your 'proportions', cause:



... which is never good... BUT, if you do get the 'mix' just right, it sometimes can =



... which is GOOOOD!!!
j

(sorry for the mini-jack... this WAS about your TEC...

LOL! Exactly!

No worries. I enjoy the way the thread is going.

However, based on the calculations from the website I posted above.... http://www.customthermoelectric.com/..._analysis.html

I get an end result of a 127 pellet TEC, 2 amps = Imax. So, how many watts is that? Voltage varies on the current flow so I'm not exactly sure on how to calculate this one. Also, I don't have a meter capable of AC resistance so I can't properly test the TEC's for continuity.

[The_Doctor]

...mini-jack...

?
That is NO way to drink!

Which is daft coming from me, I can make a bottle of whisky last months.


Re TEC's, one way to go is look at the supply, if you can enable it and measure the voltage. Or you can deduce it from counting the couples. Remember that in a TEC, each couple is TWO columns. From that count, and a Marlow or Melcor guide, you can find the voltage, and then easily deduce the power and current based on voltage and size. Theoretically this doesn't seem true but in practise, most TEC's fit a series of frequently used templates. If a purpose can use a cheaper standard 12V (Vmax of 14.5V), you can bet it will unless space constraints or other unique feature demand otherwise, because they're expensive the moment you go nonstandard.

[300EVIL]

?
That is NO way to drink!

Which is daft coming from me, I can make a bottle of whisky last months.


Re TEC's, one way to go is look at the supply, if you can enable it and measure the voltage. Or you can deduce it from counting the couples. Remember that in a TEC, each couple is TWO columns. From that count, and a Marlow or Melcor guide, you can find the voltage, and then easily deduce the power and current based on voltage and size. Theoretically this doesn't seem true but in practise, most TEC's fit a series of frequently used templates. If a purpose can use a cheaper standard 12V (Vmax of 14.5V), you can bet it will unless space constraints or other unique feature demand otherwise, because they're expensive the moment you go nonstandard.

Yeah, It's a 28V power supply that can change polarity based on weather the TEC's need to get hot or cold. So, that would be 2.8V per TEC. The thing I'm worried about is that if I get TEC's that are too big, it will short out the PS or the computer will be confused about the speed of temp fluctuations.

Based on my calculations, it seems that they are 127 pellet 2 Imax TEC's so I'm guessing around 25W but I'm not completely sure about this.

[Lasernerd]

Yeah, It's a 28V power supply that can change polarity based on weather the TEC's need to get hot or cold. So, that would be 2.8V per TEC. The thing I'm worried about is that if I get TEC's that are too big, it will short out the PS or the computer will be confused about the speed of temp fluctuations.

Based on my calculations, it seems that they are 127 pellet 2 Imax TEC's so I'm guessing around 25W but I'm not completely sure about this.

Measure the current of the good bank @12 volts divide current by 5,,
It seems TEC's are more current orientated than voltage?

[The_Doctor]

Yeah, It's a 28V power supply that can change polarity based on weather the TEC's need to get hot or cold. So, that would be 2.8V per TEC. The thing I'm worried about is that if I get TEC's that are too big, it will short out the PS or the computer will be confused about the speed of temp fluctuations.

Based on my calculations, it seems that they are 127 pellet 2 Imax TEC's so I'm guessing around 25W but I'm not completely sure about this.

No, the pellet count can never be an odd number!
Also, 25W is a damn small rating for a 40 mm TEC, you can expect that and more out of a 22mm TEC. I think yours will likely be 50W each. Give or take 10W. Hard to tell from here, but looking at the ratio of column (pellet) width to gap width can be a guide, if you compare with others to hand. (thicker columns=higher current).

Also remember that driving TEC's at Qmax is horribly inefficient so they won't do that. So Imax also isn't what will normally get pushed through them. Again, Melcor or Marlow guides are great for this assessment. As a very crude guide, for long life and high efficiency, the peak current pushed will likely be half of Imax unless more accurate optimisation was done (probably was for those, though maybe not, cos if you take a 14.5V TEC and feed it 12V you're about at optimal).

[The_Doctor]

Another thing, have you cracked open the dead one? It might have two parallel paths in there. Very unlikely if there are 127 couples (254 pellets) because 127 is a prime number, but if any are filled in with conductive blanks, other geometry might be used, and looking at the innards is the best way to tell. I doubt it is unusual like this, but the consequences of not knowing for sure might be big, so rule it out with a look at the tracks in it.

(And an error to correct, I said 14.5V earlier, it should be 15.4V according to Melcor, though I think some cheap commercial ones are specified Vmax 14.5 for a 12V supply).

One thing I don't get, is that 28V. It's a low voltage for a series of five 127-couple TEC's. It suggests they were deliberately underdriven to avoid stress. My best guess so far is they're either 33W types, with Qmax of 33.4W, Vmax of 15.4V, Imax of 3.9A, or 50W types, Qmax of 51.4W, Vmax of 15.4V, Imax of 6A. The second is cheaper, more widely used. Melcor's part numbers are CP1.4-127-10L and CP1.4-127-06L. Both are 40 mm types.

[Anthony]

maybe this chinese supplyer has something usefull.

they have different 40mm tecs


http://www.hebeiltd.com.cn/?p=peltier.module

[The_Doctor]

You'll even find perfectly good ones on eBay, stripped out of stuff. Dead cheap too, and often ten at a time. But you have to know what to get, wherever they come from.

[The_Doctor]

I get an end result of a 127 pellet TEC

Had a rethink... How did you get that value? Did you do a multiple of two adjacent side counts and jump to the 127 value as a near standard? If so, then there are actually 126 pellets and 63 couples. This makes much better sense of that low voltage. Two problems with this though, the current would be double what you expected for a square TEC of same size, it would be around 4 amps or more into a device with Imax of near 8 amps. The other is that 63-couple TEC's as big as 40 mm square are rare. As far as I know, nether Melcor nor Marlow do one as standard, and there is little or no reason to use a nonstandard TEC in that device. Also, 63-couple devices aren't usually square, but rectangular, half-width on one axis. Just trying to cover all I can think of, but this is the blind alley, go with my earlier post if you want my best answer.

If you look carefully I bet you'll see 254 pellets, 16x16-2, one missing in each location where the wires go. 127 couples.

[300EVIL]

Had a rethink... How did you get that value? Did you do a multiple of two adjacent side counts and jump to the 127 value as a near standard? If so, then there are actually 126 pellets and 63 couples. This makes much better sense of that low voltage. Two problems with this though, the current would be double what you expected for a square TEC of same size, it would be around 4 amps or more into a device with Imax of near 8 amps. The other is that 63-couple TEC's as big as 40 mm square are rare. As far as I know, nether Melcor nor Marlow do one as standard, and there is little or no reason to use a nonstandard TEC in that device. Also, 63-couple devices aren't usually square, but rectangular, half-width on one axis. Just trying to cover all I can think of, but this is the blind alley, go with my earlier post if you want my best answer.

If you look carefully I bet you'll see 254 pellets, 16x16-2, one missing in each location where the wires go. 127 couples.

My Bad,,, I meant to type 127 "couples"... They are 40 X 40MM, 16 x 16 pellet TEC's The pellets are approximately 1.6mm squared.

Also, all 10 TEC's are run in series to the 28V supply.