Originally Posted by Ranger1
How much power does a relay use ? I mean how much does it use to activate ? Thats very little current right ?
It depends on the impedance of the relay's coil. Typically they are rated at something like 75 ohms. So on a +12 VDC nominal circuit, that would be a draw of 12 VDC / 75 Ohms.. or about 160 mA.
And I think that's the worst case. I believe that some relays may actually offer more impedance than that.. more like 200 Ohm.. which would result in a 60 mA draw.
Yes, that's very little indeed. At least for automotive applications.
Edit: Although asked for power.. didn't you. 75 Ohms on a 12 VDC circuit gives you 12 VDC ^2 / 75 Ohms.. or ~1.92 Watts.