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Old 14-10-2016, 05:41 PM
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wasyoungonce (Brendan)
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Hi Pat...good point.

I will have to fiddle my variable PSU only does ~1A. I might have a 9V old DC PSU around. Other than that...I have a 13.4V DC unit...oh and a computer PSU I made variable output....ha just the ticket!

I'll get back.

Brendan
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Old 15-10-2016, 06:35 PM
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Ok now we are getting somewhere.

Ran the TEC at 6.95V DC, pulled 1.5A max, ambient23C have cold side at .5C (...now at .1C) hot side at 22.8C. I have a small heatsink on the cold side (makes it easier to clamp together) and this probably adds some thermal mass anyway it is not working much better. This cold side is in a small plastic box to try retain some thermal efficiency.

It appears the hot side on the heatsink isn't getting hot enough I expected far hotter! Which I guess is limiting the cold side? My guess is that this should be able to get down to -5C but it's being limited atm...by what?

Anyway thanks Pat and Luka now I have a point I can work on.

Oh Kemal emailed me and said he had a quote from PCBway to make the PCBs and populate them with parts. See below. He was interested in going this way as he cannot do the PCB soldering.

Basically he wants to know if anyone is interested? If you are contact me and I'll put you in contact with him. IMHO this is not necessarily a bad way to go although I felt their parts cost was a little high...anyway if enough people want this ...maybe this is the way ahead?

Anyone?
I have the quote from pcbway(china).
They make the pcbs for the advertised price, so 10USD for 10 pieces.

For the assembly; 1 unit is 155USD 10 units are 180USD and 20 units are 335USD

For the components; 1 unit is 213USD 10 units are 861USD and 20 units are 1722USD

I havent spoken about the shipping cost but probably they will make it free with government post or maybe even with DHL.

As you can see it is not viable to order only one unit, it has to be more. If 20 people are in it will be 103.85USD per person which is a good price. But customs would become an issue, at least in Turkey it would. Chinese sellers declare lower values if asked but the quantity would raise suspicions. Im guessing it is similar in Australia. Although for extra money they would ship them separately to each individual.

Cheers, Kemal


Brendan
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  #303  
Old 15-10-2016, 07:06 PM
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wasyoungonce (Brendan)
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Out of interest sake adjusting the TEC voltage to 6.0V DC (keeping the HSF fan @12V DC) saw a warming on the cold side heatsink to around 1C. I suspect between 12V DC and 7 V DC there is an optimum efficiency setting for this TEC.

I had read TECs were better at around 50% their max ratings voltage wise but have never explored this.
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Old 15-10-2016, 07:13 PM
pat30 (Patrice)
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hi brendan,
my peltier to have the best results with 5V / 2 amp you really try different voltage, you do not have the possibility of further lowering the voltage?

and too powerful fan with bad results also, it must do many tests
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Old 15-10-2016, 07:22 PM
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Pat I thought the cold side is limited and dependant on how much heat you could move away from the hot side. My hot side isn't hot enough meaning the HSF is almost too good.

I'll try a different voltage. I have a variable computer PSU and I can tap into the voltage rails and vary them up/down. Lots of settings to try.

edit:
Ok @5.2V DC TEC power, @1.1A, cold side 1C (and dropping slowly), hot side 19.7C (and dropping slowly), HSF fan @12V DC. I think I'm bleeding cold side to hot side .....the hot side is getting cooler I'm using a computer heatsink metal retaining spring clip and long allen key head drive shaft to hold it together. This is outside the box, I can feel it getting cold and hot side is getting cooler. I though heat flowed from hot to cold but anyway its definitely effecting it all.!

But @5V the TEC is not as good as at 6.95V! More to do on this obviously

Last edited by wasyoungonce; 15-10-2016 at 07:47 PM.
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Old 15-10-2016, 07:57 PM
pat30 (Patrice)
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Yes,the power it's just for down faster but we have the time
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  #307  
Old 15-10-2016, 10:35 PM
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Brendan, did I understand correctly that your hot and cold heatsinks are joined by metal? That will transfer the heat. Another thing to consider is if the cold side is getting warmed up by the fan from the hot side?

Did you use any heat transfer compound?

How big is the heat sink? If it is large, you could try running the thing at full power without the fan and KEEP AN EYE ON THE HEATSINK TEMPERATURE. Don't let it get too hot or you will kill the TEC. And don't do this without the thermal compound.
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  #308  
Old 16-10-2016, 09:38 AM
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Quote:
Originally Posted by luka View Post
Brendan, did I understand correctly that your hot and cold heatsinks are joined by metal? That will transfer the heat. Another thing to consider is if the cold side is getting warmed up by the fan from the hot side?

Did you use any heat transfer compound?

How big is the heat sink? If it is large, you could try running the thing at full power without the fan and KEEP AN EYE ON THE HEATSINK TEMPERATURE. Don't let it get too hot or you will kill the TEC. And don't do this without the thermal compound.
Hi Luka...its just a metal spring clip used in many older computer HSFs to clamp the HSF down. Contact surface of this is small very small but yes it will loose some efficiency between Hot/cold sides. This is a "rough" test just to find a sweet spot and if the TEC is suitable.

I'm still fiddling with TEC voltages. There does appear to be a sweet spot of efficiency for the TEC. I am getting better cooling using ~7V compared to 5V or 13V.

Yes I'm using thermal grease. I'll fiddle with HSF fans but I'll try to find the optimum TEC voltage first as I think this is the key.

Brendan


edit:
Ahh getting better results now:
TEC @7.08V, TEC I draw 1.54A, cold side @ -4.2C/hot side HSF 22.4C. HSF fan @12V DC. So its working better much better
TEC @7.42V, TEC I draw 1.6A, cold side @ -5VC/hot side HSF 22.4C. HSF fan @12V DC. So its working even better and deeper cooling.

Repeating above voltages but throttling fan @same as TEC voltage:
TEC @7.1V, TEC I draw 1.52A, cold side @ -4.1C/hot side HSF 24.1C. HSF fan @7.1V DC. So throttling allowing hot side fan to increase this a few degrees doesn't appear to help cooling capacity.
TEC @7.43V, TEC I draw 1.6A, cold side @ -4.7C/hot side HSF 24.6C. HSF fan @7.43V DC.

Now I'm at a small wall!
My variable computer PSU can only vary up/down a small range as I modified under/over voltage trip points. So I only have so much range in adjustment. Using the 5V rail I can get from 4.5V to 7.42V and the 12V rail from 11V to 18V. So I've run out of adjustment to run the TEC. I need and 8V and 9V source. Sigh... it never ends. Ireally need to try these voltages. Wonder if I can hook between 3.3V rail and 12V rail?

Last edited by wasyoungonce; 16-10-2016 at 01:21 PM.
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  #309  
Old 16-10-2016, 03:45 PM
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Ok here are results for 30mm SQ TEC TES1-12703.

1st the fan. Increasing hotside fan voltage increase cooling capacity...it spins the fan faster re-moving hotside heat more rapidly. But, at some voltages (9~11V DC) its quite acceptable to run the fan from the same voltage as the TEC and the decrease in cooling capacity is minimal.

2nd. The TEC does appear to operate best around 9.0V ~10.5V DC (11V is ok as well). Its difficult to gauge as my PSU can only go down to 10.6 on 12V rail and up to 7.43V DC on 5V rail. But the TEC at 10.6V reached -7.0C easily where my controller switched off...it's a low as it can control.

So best cooling appears to be 9.0~11V on TEC fan at either 12V or at same voltage as the TEC. Increasing above this see the capacity drop off, the cold side isn't as cold! 9.0V ~10V would be optimal as the I draw would be ~ 2 amps and this voltage suits the camera PSUs as they have to drop less across them, aka they heat less.

I'd expect to see the TEC reach lower temps when put in a thermally resistant housing...aka on the case with HSF.

It doesn't appear to matter which HSF I use the TEC never go hot enough ...max HSF hot side measured was 29.6C TEC at 10.6V fan @12V.

So this TEC is good enough for purpose to -6~-7V cooling capacity from 9~10.5V DC TEC voltage and with the fan voltage the same or 12V.

Of course these are my fans and HSFs would the results be the same of others?

Next is the 40mm SQ TEC but...this might be too larger for the case and I draw might be too high?
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Old 16-10-2016, 05:52 PM
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What was the ambient temperature or what was maximum deltaT?
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  #311  
Old 16-10-2016, 07:13 PM
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Sorry just uploaded doc to the GD on this. I didn't calc delta T yet. Suffice to say the TEC didn't perform to expected/stated values.

Was busy trying to get as much info I could. Unfortunately I ran into issues with my PSU. That said I had enough to extrapolate optimum desired TEC voltages.
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Old 16-10-2016, 10:34 PM
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Good work Brendan. It looks like the best deltaT you were getting was about 30C. This will give about -5C on a hot Australian summer night which is fine but I would like to have more spare cooling capacity (I like to overdesign things ).

How heavy is your heatsink/fan?

Few thoughts:
  • The Cam86 uses PWM to control the TEC. Optimally we don't want to run the cooling at full power (I would guess 40-80% PWM would be the optimum) meaning that deltaT will be less than in your tests.
  • PWM may not be compatible all fans, depending on the fan type. We may not be able to run the fan at the same voltage as the TEC.
  • Performance is probably what we should have expected. Firstly, the manufacturers like to overestimate the performance and also take measurements in optimum conditions. Secondly, the stated max deltaT of 67C is with no heat load.
I am thinking getting one of the double-stacked Peltier from ebay and doing some testing. Should have done it straight away as now I have to wait for delivery. I have uploaded a list of candidates to GD. ATM my favourite is:
TEC2-19003
dT max = 83C
Imax = 3A, Vmax = 12V (or 16V???)
Qcmax △T=0(W) = 15W
30x30x6.5mm
(5.78V gives dT=65C)
for about $20 on ebay or $15 on aliexpress.

Hmm... what do you think?
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Old 17-10-2016, 08:29 AM
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Hi Luka

I think this TEC will perform better wit ha proper set-up...aka in the case and with a copper cold finger, I used the small heatsink on the cold side to act as a thermal resistance. The Hotside HSF is a small computer unit. Seeing the hotside never really got past 30C much you can guess it's more than suitable.

But I was concerned to see the differential was only 30C. But using the current voltage this showed it to be at 27W which was the Qmax for the TEC. I think this TEC can give some more and I think its right in the range of supply voltages I cannot do at,...aka 9V DC ~ 10V DC. I say this because the rated I of the TEC is supposed to be 2A and I noted at the voltages I had it at either 1.6A or 2.4A!

I agree using this TEC doesn't leave much headroom for PWM control. Would have liked to see -10C on cold side. I need to buy another cheap TEC controller one that goes lower than -7C! Also do something about my PSUs. I have a linear adjustable...but it won't supply the current required. Need to rectify this as well.

With this info on this TEC...unless I can squeeze -10C out of it I don't think its suitable because it leaves no spare capacity!

Yes a dual stage may be the way to go. Looking at your suggestion now.

Brendan
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Old 17-10-2016, 05:50 PM
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Luka or anyone else. Does anyone have an idea on a suitable TEC module I can buy and try? Looking for something max 3A ~9~11 VDC and probably a Delta T of 40C. Looking to cool to at least -10C using minimal volts and current.

Also anyone know of a decent TEC around these parameters?

Actually any voltage from 9~12VC is ok but wanted to limit I draw and footprint size. Mainly looking for a 30mm SQ TEC size.

Also anyone one else have one of those 12V cooler controllers one that can go to at least -40C? Mine, WH7016R only went to -7C and I need a lower temperature control! I'd prefer the ones that have a separate fan output as you can set the fan to keep running when TEC is off...helps stock thermal shock.

Yes this is not PWM control but they are useful for testing TECs.

I also have to quickly get a variable DC supply or up to 5A. My "ad Hoc systems" need a better solution!

Sorry for the ask but I have to get onto this all quickly as I'm dragging the chain a little.

Brendan
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Old 17-10-2016, 06:08 PM
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Quote:
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[*] PWM may not be compatible all fans, depending on the fan type. We may not be able to run the fan at the same voltage as the TEC.
If Cam86 PWM controller firmware is same as in Cam85, PWM frequency is too low to connect fan parallel to TEC. In the range of approx. 0.5Hz or even lower.
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Old 17-10-2016, 06:38 PM
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If Cam86 PWM controller firmware is same as in Cam85, PWM frequency is too low to connect fan parallel to TEC. In the range of approx. 0.5Hz or even lower.

Yep sorry I didn't comment on this before but yes base freq may not be suitable for fans...especially the mag-lev computer types. Generally its fine to run the fan from 9~12V ...depends on the HSF performance. Generally the faster the fan the better cooling but some lower fan speeds are acceptable. Depends..If we get a suitable TEC @9v DC we have to test if the fan can remove the heat enough at this voltage. If we are talking >2.5A...I'd say yes....at a guess.

Just going to buy a cheap TEC controller wit ha bigger range doe TEC testing. Its no PWM...but you get a good idea is the TEC can fit the range we need.
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Old 17-10-2016, 10:09 PM
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Bren,
I have a couple of TEC1-1270240 units, 40 mm square, supposed to have a Dt of 70 deg[URL="http://www.thermonamic.com/TEC1-12702-English.pdf"]
Connected to my 3 amp 0 to 30 v supply I find that Dt maxes at around 20 deg with a 50 mm x 50 mm x 1.5 mm plate for a load with a small HSF. Hot side temp does not go over 30 deg ( ambient 22 deg. Cold side temp drops to temp in about 4 min.
Temp 3.2 deg @ 9 V 1.88 A
Temp 2.4 deg @10 v 2.18 A
Temp 2.4 deg @ 11 v 2.3 A
Temp 2.5 deg @ 12 V 2.48 A
As you can see with only a small load the performance is a mile away from the stated performance and increasing voltage beyond 10 volt does nothing but burn more power.
I'll try it with some insulation as soon as I get a chance.
PS Test was with fan running at TEC voltage.
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Old 17-10-2016, 10:51 PM
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Brendan, before I forget, I believe that there is a "typo" in your Peltier specs. TES1-12703 should have Imax = 3A and not 2A. The last two digits of the model number represent the Imax in Amps.
I noticed that lots of descriptions of Peltiers on ebay have copy/paste errors, even for the same or for different models. The numbers can, at best, be used as a rough guide. And I am sure that the manufacturers are not telling the truth anyway...

I doubt that a single stage Peltier will get the wanted temperature differential. Few pages back in this thread Patrice had deltaT of 32C without sensor with TES1-6303 (3A TEC running at 2A). I don't remember if the Ukrainians got it much better with a single TEC.

Filip got deltaT of 60C (see here) with a custom dual-TEC stack, again running his TECs at 1/2 and 2/3 of max current.

Dual TECs have the maximum deltaT of about 80C compared to 60C of single modules. That is a 20C better starting point. It also means that the TEC does not have to work as hard to achieve the wanted deltaT which means that it is operating in more efficient region. Keep in mind that our heat load is very low.

Looking at power consumption:
Your TEC uses 15.4*2 + 28 = 58.8W of power to remove 28W of heat.
(Or if I am correct and it is 3A than it uses 74W)
TEC2-19003 (which I mentioned few posts back) uses 16*3 + 15 = 63W of power to remove 15W of heat.

For 2A case the TEC2-19003 is only 5W more power hungry but it is more efficient for our purpose and optimised to get bigger temperature differential. This is what we are after.
That's why I liked the TEC2-19003 and will order one tonight to do some tests.

Also it is difficult to compare each other tests as everybody is using different heatsinks/heat loads/fans/power etc.
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Old 18-10-2016, 06:32 AM
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wasyoungonce (Brendan)
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Hi Gary and Luka

Pretty much then what I found:
10.6 (optimal voltage) x 2.4 (amps) + ~30 (QTemp measured) = 55W....which is pretty much as you said.

I agree this TEC performs close to specs but not quite but is not enough for our needs. We need either a much better performing single stage...which probably won't happen given volts and amps. I have a 40mm SQ TEC I've yet to try though. Gary I found just putting the cold side in a box helped retain some cooling performance. Actually a lot of performance. The figures I obtained would be better in our set-up given better insulation etc. But Luka is right....we need a TEC to coll to around -5~10C at around 40~60% PWM power. This TEC will not achieve this.

If the 40mm TEC falls short then we must go dual TEC. I might try something like flip did cut up my 40mm one and fit it to the 30mm....FrakenTEC!

Luka, do you want me to obtain a dual TEC2-19003 as well...aww heck I'll just do it as well! I'm also ordering a better controller...like the WH7016K. Yes they are not PWM controllers but they are ok for running tests to get an idea. Also I keep running out of Temp probes!

I'll do something about my PSUs as well....gawd its a long road!

Thanks Gents

Brendan
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  #320  
Old 18-10-2016, 07:33 AM
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From my cold finger dslr work i know how important the bond is between the TEC and the sensor back, i trust you guys are using high quality thermal paste like Artic Silver, some materials are not very efficient and the pads while potentually less messy are lower in efficency. Good 55-60w TECs can require as much as 6amps and i never used stackibg fir that reason. I am amazed at how my ASI1600MM-C manages to produce a delta T of 45C out of a 2amp input, on a chip just a little smaller than APS-C. If you can work that out it makes remote site operation much easier on power consumption.

Keep at it, i enjoy your discussion.
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