voltage vs amp help

[skullkeeper]

i have an easy ? for some of you .

ok i have a Peltier im running with 2 12v pc fans.
the Peltier is rated 45.6w 12v (15.2v max) 3amp
im running the Peltier and 2 fans on a 7.5v 3a ac/dc adapter
i have a 12v 2a ac/dc dapter laying around


? what is better more volts or more amp?

the Peltier is cooler with both fans hooked up compair to just one even if the second one isnt blowing on the Peltier heatsink cooling the hot side so im guessing its a v vs a thing

[ph_christensen]

Can you draw a schematic. it sounds like you have the fans ran in series with the peltier, limmiting the current.

[ph_christensen]

using ohms law

your peltier has a resistance of 5.06 ohms

45.6 / 15.2 = 3 amps
15.2 / 3 = 5.06 ohms

so at 15.2 volts you are going to need 3 amps just for the peltier.


for 12 volts:

12 / 5.06 = 2.37 amps
12 * 2.37 = 28.44 watts

for 7 volts:

7 / 5.06 = 1.383 amps
7 * 1.383 = 9.683 watts



So With 7 volts you are only going to draw 1.3 amps at most and you are only going to use about 1/5 of what your peliter is capable of. With 12 volts you are going to use 2.37 amps and you are going to use about 1/2 of what it is capable of. and at 15.2 volts you are going to use 3 amps.

[I_Forgot]

A Peltier device is a diode. It is a nonlinear resistance, so the resistance will vary depending on the current run through it. If you're trying to match the manufacturer's ratings for the part you'll need to match the specified current (just like an LED).

You want to use a current sourcing power supply, not a regulated voltage supply.

I_F