Fan Speed Control

Gdetrailer wrote:


Which is why I am saying you are going down a rabbit hole.

You have two different "efficiencies" at work here.

1 is current draw of the inefficient brush can motor.

2 is lack of air movement of the fan blade design.

This is why I mentioned trying a computer case type of fan, the motors are high efficiency brushless PWM controlled motor and well designed fan blades that make the most of getting max air flow for the RPMs.

If you dig around you can find a 4" computer case fan that draws less than 1A and gets well over 100 CFM of airflow which is more than twice the airflow at 1/3 the amperage of what you now have. Get the right one that runs at a lower RPM and they tend to be very quiet also as a bonus.

HERE is just one example. That example is rated roughly 70 CFM at a noise level of 25 DB which is very quiet and runs at 1700 RPM max at 1.08W of power. 1.08W at 12V=.09A!!

Yes, you read that correctly one watt of power an yet get 70 CFM of air flow.

Full specs can be found HERE

The only downside to computer case fans it they are not designed to be reversible, but buy two for one each direction and switch between them.

I have converted my trailer fans over to computer fans yrs ago, much less noise with a lot more air movement with a bonus of less current draw.

This is all true about brushless motors and better fan designs being much more efficient. However it is also true that a simple and cheap PWM controller can significantly increase the efficiency of the existing fan on all but the 'max' setting. Re-engineering your fantastic fan to use a PC fan is a pretty major undertaking, adding a PWM controller in line with it is fairly easy.