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Measuring TEC efficiency

Light superglue

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Sometimes I see talks about using TECs to cool high power lasers but no one gave here any info about numbers - TEC efficiency, consumption etc. And apparenly there is no specifc thread about TECs on LPF.
So sometimes I do experiments to mesure these numbers. Just for fun but for info as well.
Last year I dismantled so called "Beverage cooler&warmer" from ali. It cooled 300g of water put inside of the can at rate of half ºC pro minute from rt to about 2-3ºC (that took 1h but at rt cooling started at rate of 1/2 degree pro min).
Knowing that 1 calorie (needed to cool 1g of water at 1ºC) = 4.2 Ws, it makes 10.5W of heat extraction while energy consumption (as was given in specs) was 12Vx3A = 36W.
So the TEC inside must have been 29% (10.5/36) efficient (if we only care about wasted energy).
After that I took the thing apart - the TEC inside was not bigger than ones purchased from ali before.

This year I saw that ali had more powerful TEC based coolers there - so called "Ice cream makers". One of them I already have dismantled earlier (was posted in NUBM31T thread) but this time it was a bigger one with 110W consumption given in description.
To have precise numbers I soldered a V/A meter into the TEC line and mesured the total consumption of the whole thing incl. motor and fan with a Watt counter. So here it consumes 115W but TEC in it only consumes 92W (4A at 23V). Once turned on it starts to chill 500g of water at a rate of 4.2ºC pro 5 min = means takes 2100 calories in 5min = takes 29.4W (32% of 92W) from water to HS.
So I found the TEC efficiency to be 32% isothermically (I mean at start when temperatures are equal from both sides. Then dismantled it and check how big the TEC inside was (70x50mm)!!!
It also had huge HS (820g of Al) and huge fan and the Al bowl fully isolated by adhesive foam - and there again were no screws and I did not try to take the bowl out this time...
 

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Alaskan

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Great info. I've purchased large 62 x 62 mm TEC's rated at 570 watts in the past off of ebay and was disappointed in how much of the specified wattage was waste heat from the device itself which greatly limited their cooling capacity.


Used them in this device: https://imageevent.com/qdf_files/technicalgoodies/experimentersfolder/irandlightwavecommunications/irledandlaserproject
 

hakzaw1

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About to try out a TEC from an IglooPerfectKool 12 vdc 'ice chest' that also heats too. kinda large for our uses BUT..MYB cool copper water line and pump. Condensation can be a problem with DIY TECs
 

Light superglue

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Hi Alaskan,
I do not like high amperes because they are difficult to maintain over a decently long curcuit, I would prefer to have several TECs in series with not more than 3-5A running through them.
Yes 570W TEC had to produce these 570W in addition to the heat you wanted to extract from your LEDs.

Thinking that my ice maker has 820g HS to dissipate heat from 92W TEC you needed a really big HS - maybe 2.5-3kgs of Al and several big fans - to do the job well!

Hi Hak,
Which Iglo do you mean? Once I opened a cheap 7.5L cooled box from ali for 23EUR and there was only one small 12V 3A TEC inside which you can find for 1-2 bucks elsewhere.
 

paul1598419

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If you need to remove a lot of heat from anything a TEC is not going to be the most efficient way of doing that. Water cooled Argons are a great example of this. Seems that water cooling is still preferred over TECs.
 

Alaskan

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I used high amperage TEC's because the 12-13 VDC was being supplied by my truck with a 100 amp alternator to keep the battery up. All depends upon what you are doing, so I choose that.
 

Alaskan

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I could, but then I would have hoses and all to deal with, the truck is just a power supply, the laser had a long 25 foot run of welding cable from the battery to where it would sit outside, plus if I used water to cool it, then I couldn't work on it inside without a water cooler and I had a 60 amp 15 VDC power supply to use inside..

 

paul1598419

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Isn't that one of your IR lasers that used many diodes, Chris? I remember you working on that back when you started here.
 

Alaskan

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It is, I never installed the IR diodes, just had sixteen two watt 450 nm diodes and 1000 watts of RGB. One hell of mostly non-coherent RGB mood light, I would point it at those mountains in the background and light them up with RGB and blue lasers.
 

paul1598419

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Yeah, I never used the M140 diodes for multi-builds, but sure made a lot of singles with them. Still have one doing more than 2.2 watts.
 

Alaskan

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They were cheap & the divergence decent. This was like what, 5-6 years ago? We have more options now. If I had the diodes available then which we have now, at current prices, I would have chosen something else.
 
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