I'm no expert, but from playing with Peltier modules I understand that, for a constant temperature difference between the two sides, they behave almost as a resistive load, with an almost linear relationship between input voltage and consumed current.
So, assume I have power supply flexibility to run the things at any voltage I like. That means I can make them consume any amount of current I like, below the max. So a TEC1-12706 is rated for max 6 amps, and a TEC1-12703 is rated for max 3 amps. But if I run a 12706 and 12703 at different low voltages so as to make them each consume the same total watts, will they perform differently?
From what I understand, when you run an individual Peltier module at any lower voltage than its maximum voltage, two differences are:
- It is more efficient, in that it produces a lower ratio of waste heat compared to the useful heat pumped thru it.
- It can only sustain a smaller temperature difference between the two sides.
Do I understand those two points correctly?
If so, still I can't understand what current rating of Peltier I should choose. There must be a difference, otherwise they wouldn't bother to make all the different ones.
Basically, in practice, assuming I have complete choice of input voltage, when are higher-current modules better, and when are lower-current modules better?