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Friday, September 14, 2018

Speed Control For Fantastic Fan in FWC

Most of the time my Fantastic fan is too high a speed on low setting.  The Fantastic fan comes with a speed switch that gives 3 speed settings.  I can just open the vent on the Fantastic Fan for natural airflow, but some mechanical draw helps.

Note: I had upgraded my Four Wheel Camper’s Fantastic vents because  the rear one was a vent only and this is where I cook.  The front one over the bed was powered.  Here is my modification on this conversation.

(Above is the upgraded vent only to power vent/fan with temperature control)

My problem:

When I just want some powered exhaust from the vent with my window cracked open below, I don’t need the fan on spinning very fast.  I also would like to conserve my solar power LiFePo4 battery system with lower current draw.  A side benefit of the slower speed is the fan runs much quieter for sleeping.

The answer:

Below is the PWM speed controller that I bought from Amazon.  What Pulse-Width Modulation does in this case is sends 12 v on and off.  The faster the pulse the faster the motor spins.  When the pulse is off there is no power draw.  Therefore a 50/50 cycle the motor uses half the current.

Here is what WIKI has on PWM

I needed to test the current draw to ensure that the 2 amp PWM will work on the Fantastic Fan. 

I dropped the cover of the Fantastic Fan and put my clamp meter on. The inspection showed 2 amp controller would work.

I then temporarily wired in the PWM and tested it.

My test showed that the PWM would adjust the speed of the fan from full speed to off.  I set the speed to be a constant light draw and I was only drawing .59 amps.

This low draw with lower window cracked will provide powered heat extraction cooling the inside of camper and making my Engel compressor fridge run easier.  Since I have the temperature control on the Fantastic Fan when the fan turns on my solar battery system will have no problem providing the power needed.

The spot I was able to fit the PWM was next to the speed switch.

This is the way it looks with PWM installed.  Note the PWM has a light on the circuit board that shines through the white plastic so you can see that it is turned on.

Above is the installed PWM controller ready to adjust the speed to what I want it to be.

It works in both exhaust venting or power fan pushing in air.  As stated I have it set to start on venting on low speed once it gets hot inside the camper by setting the temperature control in the upper right corner in the picture above.


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