mystery pelt here.... help solve the mystery!!!

TheMightyBuck · Apr 9, 2003

i have a peltier here, i got it two years ago from a friend....

i have no idea what brand, wattage, etc.......

i set up a calorimeter to see if i could calculate it's rated wattage, but i got .03 watts, and my calculations and equations were correct, so i think my setup was incorrect, or not sufficient, because .03 watts is pretty damn small.

anyway, does anyone know how i can test this thing to see ::about:: how much it's rated for?

thanks....

Norrko · Apr 9, 2003

Pics... Got any? Is there some kind of text on it?

/Norrko

doc · Apr 9, 2003

If you could describe your method, maybe I can help you get it right. Some years ago I delveloped a method of getting Qmax and dTmax on the fly, but it requires aleast 2 thermal couples, a const. temp sink and a data logger or someone that can do that fast.

ZedBias · Apr 9, 2003

Heard and seen loads of stuff regards to Pelts but what are they and how do they work.

Ct. Strangelove · Apr 9, 2003

you need to find an ammeter. check the amps it sucks then you can figure out its wattage.

TheMightyBuck · Apr 9, 2003

i'd post a pick, butit'd be pointless... the only writing is a small h and c that i put on the hot and cold sides. i don't have anything other than a radioshack outdoor thermometer to measure temps with.

the pelt is 40mmx40mmx4mm, red and black leads

the calorimeter that i build was two styrofoam cups, filled with water, and i sandwiched the pelt between two heatsinks (amd stock and volcano7). i put the coldside heatsink into the water in the styrofoam cup, and the hotside with fan abover the lip of the cup. i insulated from the peltier to all around the cups, with the radioshack outdoor thermomete probe in the water.

then, turned on the pelt and fan, and recorded temps every 30 seconds. after the water temp got down to like 2C, i got bored, and calculated how many jules of heat was in my volume of water, and how long it took to pump 'em out.

i'll look for my data, but i doubt i still have it layin' around.

the psu i was using could throw out 17A at 12V.

i'll look into getting an ammeter.

doc · Apr 9, 2003

Did you consider the mass of the heat sink in the water and it's specific heat? After all it must change it's temp as well. As for an amp meter, a cheap volt meter for about $20 will do just fine.

PS Buy the way, cool dog.

TheMightyBuck · Apr 10, 2003

ty, her name's gert, 7 years old, beagle... puppy forever.

anyway, yes i assumed that the heatsink was the same temp as the water, for simplification purposes, and added it's heat into the equation too.

also, ,the specific heat capacity of aluminum is much, much, much less than that of water, so that would not be the cause of my error, although i did factor it in.

so i get a multimeter, set it to about dc amps, then fire up my pelt (with sinks, of course!)...... do i put the probes of the multimeter so that the meter makes a parralel circuit to the pelt circuit, or should i make the multimeter like a "switch," hooked up in series, so that all the pelts current goes through the meter also??

i dunno, so i thought askin' would be good idea.

Lt. Max · Apr 10, 2003

i thnk u should just tap into the circuit of the pelt with the ammeter simply as that.. what voltage are you running it at?

doc · Apr 10, 2003

Ok, I think I know what you missed. As you pump the heat out of water and HS, it gets colder and colder, the TEC pumps less and less heat as it approaches dT max. At dT max, Qc (heat pumped) goes to zero, so you must calculate your heat pumping with smaller increments of delta T of the water and the temp difference from the hotside to coldside is near zero. Qmax is defined at dT=0. Try this and see if it works, if you need more details let me know. Dont worry about the ammeter yet!

TheMightyBuck · Apr 10, 2003

well, i'd like to do that, but the thing about lowering my delta T would be that i'd have to cool the hotside down, and i don't have much to be able to do that...... all i have is heatsinks.... any suggestions as to how to cool the hot side, to keep deltaT under the deltaTmax?

Diggrr · Apr 10, 2003

I'd check the multimeter closely before using it inline with TEC, some of them (like mine) won't take some TEC's amperage.

If you have it between two heatsinks already (asuming you also used thermal goop) why not fire it up with a battery charger, and just read the gage on the charger?
being a 40 x 40, it's prolly 12-16 volts and not 24.

TheMightyBuck · Apr 10, 2003

will a battery charger be able to be read with the precision that i need? i mean, can u tell the difference between 15 and 17 amps on a battery charger?

Diggrr · Apr 10, 2003

I can on mine (Sears brand).

TheMightyBuck · Apr 10, 2003

i'll try that out... although, my batt charger is a "viking" and i think it's older than me.

ty

ZedBias · Apr 11, 2003

I did ask ths ealrier, but I didnt get a responce, No worries? But what is a pelt?? I have heard so much about them but dont know what they are??

doc · Apr 11, 2003

Use warmer water in the cup to start with, this should put dT closer to zero. Make sure to let the HS in the cup to come up to temp before starting. With Tc being somewhat higher than room temp, Qc will higher than at room temp. But you should still get a good ball park number.

For the question, "what is a pelt?". This is a solid state device that can cool, heat, produce power and can made in many different sizes and shapes. There are many good threads and articles at OC that can explain more.

[EG]~NaTz~ · Apr 11, 2003

pelt = heatpump.

what is an an ammeter? does it measure ampres? or more?

TheMightyBuck · Apr 11, 2003

well, i hooked up the pelt and heatsinks to my 12 volt battery charger, which said on the box that it was "6 amp"

i put the hot side in ice water and the cold side is where i attached the fan this time, to warm it up with room temp air. this should actually give me a negative delta T, but hey, it works.

anyway, i rigged it up, and right away, it read 4 amps, and as the ice melted, and cold side got cooler, it started to draw less and less current.

i tried it again, with fan on hot side, and cold side just in ambient air, and i got the same results, 4 amps, then slowly falling.

with my multimeter, i measured ~10.5 V in the circuit.

does this mean that my pelt is 42 watts?

if it does, that sucks.

yes, an ammeter measures amperes. a multimeter measures multiple things.... the ultimate multimeter would measure volume, length, mass, current, volts, temperature, ohms, pressure, force, inductance, and capacitance.

something that measured volts and current would also be a multimeter.

Les56 · Apr 12, 2003

TheMightyBuck said:
....................
does this mean that my pelt is 42 watts?..........

It does not.
Amongst others a Frost-72 ( Qmax=62,Vmax=16.3,Imax=6.2,dTmax=72, 40x40x3.9mm) will probably use about ~ 4 amps at 10.5v under those thermal conditions.*

* From the "Kryo TESC" portion of the Kryotherm software http://www.kryotherm.ru/soft.htm

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