Thermal Electric Generator Small Peltier Units

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
Hey guys, new here.
Having trouble with a small class project I was intending to present to the class next week.
I wanted to demonstrate the use of Peltier panels to generate electricity.
I think I may not have sized the motor/peltier panels correctly.

I'm using: 3X https://www.amazon.ca/dp/B00CDK1SL0/ref=pe_386430_30332290_TE_3p_dp_1
with 1X https://www.amazon.ca/dp/B0098WE9O4/ref=pe_386430_30332290_TE_3p_dp_2

Peltier panel:
Model: TEC1-12706
Size: Approx. 40mm x 40mm x 3.8mm
Voltage: 12V Umax (V): 15V
Cooling power: Qcmax 58-65W Imax (A): 5.8A ?Tmax(Qc=0): up to 65°C
Operates Temperature: -30°C to 83°C
Max power consumption: 70 Watts

Motor:
  • Product Name : Micro Motor;Model NO. : 130;Rated Voltage : DC 3V
  • Rated Current : 0.2A;Speed : 12000RPM;Rated Torque : 65g.cm
  • Body Size : 27 x 20 x 15mm / 1.06" x 0.78" x 0.59"(L*W*T);Shaft Dia. : 2mm/ 0.079";Total Length : 38mm / 1.5"

Any help would be appreciated, I'm super new to this and just wanted to show my class a neat little experiment to maybe get them excited about the sciences.

The idea was I would wire the panels in series and then place them on a bowl of boiling hot water with a bowl of ice cold water on top. then the motor would power a small fan.


Thanks guys,
-J
 

wayneh

Joined Sep 9, 2010
17,496
With you arrangement of water, ice and peltier modules, have you looked at what open-circuit voltage and short-circuit current they can produce? I suspect it's far too small to start and/or run the motor. (Most motors take a bit more current to start moving than they do while running. You might be able to manually get it going if you get really close to having enough power.)

Use a multimeter, take some measurements and you'll find your answer. Consider using LEDs instead of a motor, at least for testing. That will work for sure.
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
With you arrangement of water, ice and peltier modules, have you looked at what open-circuit voltage and short-circuit current they can produce? I suspect it's far too small to start and/or run the motor. (Most motors take a bit more current to start moving than they do while running. You might be able to manually get it going if you get really close to having enough power.)

Use a multimeter, take some measurements and you'll find your answer. Consider using LEDs instead of a motor, at least for testing. That will work for sure.

Hey thanks for replying!

Unfortunately I don't have access to a multimeter, but I went out and bought a set of leds, hooked one up and still nothing.... I'm going to fuss around with my makeshift 'test rig'... which consists of break pans... maybe it's not getting enough heat to it..?

Otherwise I'm guessing there must be a faulty peltire panel somewhere? I'm not missing something basic here am I? I wired the 3 panels together red to black, then the red from panel 1 and the black from panel 3 is connected to the leads of the led....
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
I think they're just not producing enough power.... they say -30 to 83C... could i have broken them my using boiling water?
 

ronv

Joined Nov 12, 2008
3,770
I think they're just not producing enough power.... they say -30 to 83C... could i have broken them my using boiling water?
I don't think you hurt them.
Do you have really good contact between the boiling water an the peltier surface? Same with the ice water side?
Some form of insulation between the hot and cold side might also help. (Same thickness as the peltier.)
 

wayneh

Joined Sep 9, 2010
17,496
Did you have a current-limiting resistor in series with the LED (if not, you may have fried the LED)?
My thought also. I think the first time I tested a Peltier with an LED, I used just one module and a mild temperature difference. I was surprised to see that it worked.

@DohnnyBoy, you really should do yourself a favor and get a multimeter. Maybe you can borrow one. If you live anywhere near a Harbor Freight, you can get one free there if you can find their coupon. You can also find them for just a few dollars on eBay. For the amount of capabilities a multimeter gives you, it's worth it. You could diagnose and solve your current problem in seconds if you could just get yourself some data.
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
Hey guys, So I layered in some cork around the tecs, and used thermal compound on the undersid eof one container, that container sits right on the bottom container that hold the boiling water, the boiling water is like milimeters away from the bottom side of the tecs. then that container is wrapped in towels.... there's no way the the heat is going anywhere but up through the peltiers....

And I double checked and they are in series. red to black red to black.

Still nothing. I've just tested it again to see... reversing the led half way through to double check the current wasnt going the wrong way... I heard leds are specific like that.

Still nada.

You're right about the multimeter, I'm going to try to get to homedepot today. But I mean, the only thing I can guess now is that the tecs are faulty or something right? or at least one cause their in series.... aahhhh What a pita.
 

wayneh

Joined Sep 9, 2010
17,496
Look at it as a learning opportunity. Those can feel like a pita while you're in the middle of them but you'll come out the other side knowing more than you do today. Your meter will reveal where your problems are.
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
Hey guy's thanks again.
I'm going to rona now to get a mu
Disconnect the Peltier modules and try using them one at a time to drive the LED (with a ~1k series resistor!).
Wayneh: totally agree with you. Before this i was totally afraid of figuring out how the heck to use a multimeter. Now i just bought one, have watched a couple videos, and I'm excited to play around with it... Shit! I forgot to buy batteries! Aaahaha damn, knew i was forgetting something.

Anyways, alect: why do you say i should use a resistor as well as the led? I have tested the LEDs with 2 double A batteries (pulled from my TV remote, lol) in series after try ing the tecs, and it litup. So I'm fairly confident they didn't blow.

Do you think the LEDs have some sort of over over volt protection or something? ... I doubt it, they look like standard little guys.
 

wayneh

Joined Sep 9, 2010
17,496
Do you think the LEDs have some sort of over over volt protection or something? ... I doubt it, they look like standard little guys.
No, you just got lucky that the AAs were within the narrow operating voltage range of the LED. Too low a voltage, the LED cannot light. Too high, the current will exceed the spec for the LED and ruin it.

Using the resistor ensures that the LED will not be damaged by a voltage all the way up to 12V or more. (Any resistor in the range of 220Ω to 1K would probably be fine unless you know you might have a voltage source over 9V.) With a resistor in series, the LED will still light at lower voltages, it just won't be as bright, and it won't be ruined at a higher voltage.
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
Okay I tested it.
And I'm getting a constant .003 Volts... sometimes it jumps to .020 V.....
When I do a continuity test I get nothing.
 

wayneh

Joined Sep 9, 2010
17,496
Okay I tested it.
And I'm getting a constant .003 Volts... sometimes it jumps to .020 V.....
When I do a continuity test I get nothing.
Is this with a temperature difference across the Peltier? I would expect a near short when measuring for continuity. Your module is similar to a 1.2Ω resistor, since it will draw ~10A at 12V. I'm beginning to think you have a dud.

Do you have a 5V source available, such as an old computer PSU? I've tested modules by connecting them briefly to such a source. It'll draw about 4A and the cool side will feel ... cool, while the other side will get hot. Don't leave it hooked this way more than 5 seconds or so, since the hot side will overheat. It should only take a second or two to feel a temperature difference develop between the two faces.
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
Because I've been using boiling water on one side, and ice on the other... do you think condensation could have built up in the tecs and shorted some of those little modules things inside the panel?
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
Heyo, So i tested each panel individually. one seemed to be a dud. Re rigged it with the two other ones... and I'm currently pulling 1.72 volts. Enough to power the single red led. Very dimly though.
I dont get it though, these things were rated for what 12V... I mean I'm guessing that was over a -30 to +65C deltaT. but still, Lets say I'm at +10 on the cold side... and probabaly pretty close to 63 (probabaly much closer to 80C on the hot side.... I should be pulling what like atleast like 4 or 5 volts, maybe 3 conservatively.. I havnt broken 2 yet.... actually no cause that was for a single panel, I have them in series so I should EASILY be wayy wayy above 3 volts.
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
I figures I'd leave it and just monitor the voltage and its starting to drop now so I iunno whats going on... it would be nice to have some temperature probes i guess.

I think I'm maxed out on this one though gentlemen.
 

wayneh

Joined Sep 9, 2010
17,496
I dont get it though, these things were rated for what 12V...
That rating is for the voltage that can drive the module near to its maximum rated current. It is not what you'd expect from using the module "backwards" as a generator. We see a similar misconception here often – people will spin a 12V DC motor and wonder why they don't get 12V out of it when it's used as a generator. It just doesn't work like that.

The voltage of the module will depend on the ∆T across it but maybe also on the absolute temperature. Anyway, when you see it change with time I would suspect unstable temperatures.
 

Thread Starter

DohnnyBoy

Joined Mar 26, 2017
11
That rating is for the voltage that can drive the module near to its maximum rated current. It is not what you'd expect from using the module "backwards" as a generator. We see a similar misconception here often – people will spin a 12V DC motor and wonder why they don't get 12V out of it when it's used as a generator. It just doesn't work like that.

The voltage of the module will depend on the ∆T across it but maybe also on the absolute temperature. Anyway, when you see it change with time I would suspect unstable temperatures.

Ahh, okay that makes sense to me... that max 12v is rated one way but there's some inefficiency or something running it backwards.
Anyways. I appreciate all the help guys. This has been a fun little weekend project, one that I imagine I will revisit someday.
You guys have a great forum too btw. These responses were hella quick.

Take care lads.
 
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