would like to know the approximate draw in watts/amps on a coleman 12V air pump/deflater????

Question

the item in question is an air pump/deflater....not a compressor. would like to find an ac/dc transformer to power one and need to know what the draw would be on this 12v pump. thanx.

Answer 1

Most devices have current and voltages labeled on the device itself. Most likely near the pump motor or somewhere on the back. If it does not have a label, you can always measure it by connecting an amp meter in series with it. Another way might be to put a high wattage, low resistance resistor in series with the motor and measure the voltage across the resistor. (Maybe a 10w, .1 ohm resistor?) Then use Ohm's law to figure out the current. V = I R, I = V/R. So, if you use the .1ohm resistor, what ever voltage you read, divide by .1, and that's your current. You can figure out watts by P = I V.

A word of caution though... high inductor type device like motors can have very high surge current. You might blow the fuse on a simple multimeter. Also, your power source need to be able to handle the surge without blowing a fuse... Oh, one other thing, your stall current on a motor is also very high compare to the typical run current. Your power source needs to be able to handle that high load...

Answer 2

Well, we will do a little unit analysis to find out you answer.

1 Watt = 1 J/s
1 A = 1 C/s

So 1W/A = 1J/C which is energy per unit charge

V q = Electric potential energy

Volts is also a unit of energy per unit charge equivalent to 1J/C.

Your answer would be 12 watts/amp or 12 J/C or 12 volts.

Electric potential tells you the amount of energy you will use per unit charge you have. Since power (Watts) is just energy per unit time and current (Amps) is just charge per unit time, your temporal units will cancel out when you try to find Power/current (Watts/Amp) giving you energy per unit charge or electric potential (Volts).