Fan speed controller

Thread Starter


Joined Aug 8, 2009
All I am new to the forum. so "Hello"

I have a 12 v DC fan which pulls 8.0 amps.
it has 2 wires. and can easily reverse direction by reversing the wires.
my goal. is to have it pull less amps (sacrifice speed is not an issue)
can I just install a resistor? OR install a potentiometer or similar

It works fine right now its quite noisy at full speed. I tried it @ 6.0 volts
it works nice. after much investigating. Would a speed controller do the same job of allowing me to reduce the voltage draw at the cost of speed?

What would be the least expensive route? and end up pulling less amps?

This is in my vehicle and in the event its running while Im away from my car. I dont want to come back to a dead battery. hence the reduction in amperage usage

Thanks in advance all!


Joined May 11, 2009
I think the best thing would be to use a Pulse-width modulation (PWM) approach. It can be done quite simple with few components.