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Topic: Brushed fan controller, 12v 100a+, for electric fan conversion in truck (Read 74 times) previous topic - next topic

DocStein99

I want to replace the crappy clutch fan attached to my water pump in my truck.  People are pulling used electric fans off other cars and they work (mostly) to do this modification.

Unfortunately, it is more involved.  They just rig up fuses with a relay, and what ends up happening is that the full current goes to these fans endless and it winds up blowing out fuse, and they keep changing the relays which are probably not rated for continuous duty.  Also, they are complaining about upgrading their alternators to output the current needed to keep up with the electric fans.  My truck has already been outfitted with 80 amp alternator.  The fans use about 30a @ 12v when on, and much more to start up. 

I do not have one yet to test with, but obviously there are other factors involved like when a truck is running 60+mph with the wind through the radiator, and the heat - who knows how much current is being used.  I won't know until I can get a real test.

So my idea was to drive with mosfets if possible.  I make an Arduino project, send a ramped PWM signal to start the fan (SLOWLY to reduce a peak burst current) and maintain an RPM with possibly an optical encoder.  I suspect the fan probably won't need a 100% duty cycle.

Here is my question; Should I go and get some high grade mosfets and build this driver myself, or does anyone know of a strong generic CHEAP brushed PWM speed control module I can use?  Sometimes I build these things on my own, it ends up costing me more money and my time buying mosfets and parts - then 2 days later I discover some module somewhere that does the same thing for lunch money.

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