I want to power up 4-5 peltier elements TEC 12706 which have maximum voltage of 16.4V and max current of 6.4A (at 50 C). Will a power supply of 12V 30A do the job (I'm thinking about connecting them in parallel). Also in which case peltier is going to take it's maximum current? I have done experiments before, peltier does not sink more than 2A of current. Why so?
I have done experiments before, peltier does not sink more than 2A of current. Why so?
Imax is a never exceed specification. If you exceed that you might break the device.
Based on this chart if your hot side is heatsinked well enough to keep it below 50C you would expect it to draw a little more than 4.5A at start up when the delta T is 0. That is when the hot side and cold side are the same temperature. So your power supply shouldn't run in to current capacity issues.
Depending on what you're trying to do you might want to run them at a lower voltage than that. All the power that you put in to a peltier becomes heat. So while higher voltages can potentially move more heat from one side to another it doesn't necessarily result in lower cold side temperature. When I experimented with peltiers I stacked two on top of each other and found they got colder when powered in series from a 12V power supply than when they were in parallel.
You say you want to run 6 devices that are each rated at 16.4 V and 6.4 A from a 12 V 30 A power supply.
Peltiers look largely resistive to the driving circuit. If one draws 6.4 A at 16.4 V, then just linearly scaling that to 12 V is a good start. That means assume 4.7 A at 12 V. You want to run 6 of these, the total current will be 28.2 A. That's very close to your 30 A limit, so not a lot of slop or room for the numbers above to be off a little. The voltage of a Peltier does have some temperature dependence.
So the answer is it will probably work, but not with a comfortable margin. There are two things you should do:
- Measure one of the Peltiers at 12 V. That gives you the current per device directly. If that is still less than 30 A / 6 = 5 A, then it could work.
- Get a 12 V supply with current limiting, as apposed to one with foldback or a fuse. If the Peltiers try to draw a little more current than you expected, the voltage will just go down a little and no harm will be done. Of course the cooling power will go down too.
For more information on controlling Peltier coolers in general, see How to drive a Peltier element?.