Hi !
So, I've read many posts on Peltier devices, and yet, something remains unclear in my mind... If I have a 15V/10A power source (I can choose the voltage between 0 and 15V), and plug the peltier to it. If I put 12V, it is expected to use 6A. But what if I put 11V? and 10? I've read that it had an internal resistor around 2 ohms, so the easy answer would be that if powered with 11V it will take 5.5A but is that that simple ? Because I've also understood that it was not a linear device, so I am a bit lost...
Are there graphs displaying the current taken depending on the voltage?
Thanks a lot, I know it is probably stupid, but I'd love some explanation..
Have a great day
I
Yes, but they are not 2D, because the heat flow and temperature differences between the two plates are also important.
A number of physical models for Peltier devices have been proposed for use in circuit design, and a web search will find publications. One randomly chosen example: The basic Peltier model — Peltier Power
Okay, I've read both the links you've put but did not understood it very well..
How is the temperature difference between the two plates important ? Does it mean that if I repeat the experiment 10 times, I may have different currents even though I put the same voltage ?
Is there an easy way (through calculation or by reading graphs) to know how much current my Peltier is likely to take from my power source if powered with 11V ? Roughly. Is it accurate to estimate this current to 5.5A, and if not would you have an idea of a more reasonnable value ?
thank you very much to have responded so fast,
have a good evening
Yes, if the Peltier temperature distribution changes.
2 Ohms is not a bad estimate of the internal resistance at 12V, but the value does depend on the temperature in a complex way.
To use a Peltier device efficiently, it is extremely important to have heat sinks on both plates, with a thin layer of thermal transfer compound between heat sink and plate. Fans on the heat sinks will also help.
In any case Peltier devices are very inefficient means of transferring heat from one place to another. Also very inefficient for the reverse process to generate electricity from heat transfer.
Yes, I knew peltier were not efficient at all, and that without mentioning the Seebeck effect.
I had put 2 large heatsink + 1 fan (12V) on the hot side because without this, the cold face did not remain cold very long and it did actually work very well, the cold face did remain cold a very long time.
To know how much current my peltier is pumping when powered with 11V, it appears that I need to redo the experiment. I'm gonna do that
Thanks a lot for your answer @jremington,
have a good day
Quite surprised here, I 've just plugged my Peltier device to the power source (15V/10A) but for 10,2V I see 2,2A... I suspect me peltier to be broken or a fake. Does this value seem odd to you ? It's quite far away from the 5V expected...
thank you all
Why is it surprising that a nonlinear, semiconductor device does not obey Ohm's Law?
It is certainly possible to damage or destroy the Peltier by overheating it (at above about 80 degrees C unless otherwise rated), which will melt some of the semiconductor junctions. But it usually won't pump heat or conduct current if that happens.
Note that once the maximum temperature permitted difference between plates is exceeded, the the device goes into a mode that just generates heat from both plates. This can permanently damage the Peltier or at best reduce its ability to pump heat as efficiently as it could before the breakdown.