fan is not blowing much

One Awesome Inch · Jul 28, 2015

So I connected my computer fan to my electric system (fuse block & 100ah battery ). I used a 12V dimmer on Sternwakes recommendation. However the fan is not blowing much and I am not getting a breeze unless my face is 4 inches from the fan. How do I get more power into the fan so it blows stronger?

highdesertranger · Jul 28, 2015

have you tried to direct wire it? so you see what's it's supposed to do. put a vom on the feed wires to see how much voltage it's getting. highdesertranger

Gary68 · Jul 28, 2015

do those computer fans have enough "cut?" in the blades to push much air?

SoulRaven · Jul 29, 2015

Your description sounds like many others I've read about who try computer fans.

Maybe 10 years ago I approached a fellow at a computer store to ask about the possibilities, that guy wasn't impressed by the idea.

An inline marine fan would move a lot more air, in about the same diameter. Not sure whether they are speed adjustable.

SternWake · Jul 29, 2015

You fan is only rated at 0.14 amps. That would be about 50 to 60 CFM maximum, and it is about as slow as a 120MM fan gets.

Computer fans vary greatly in air moved for noise made and current consumed.

Fans without steering vanes in front of the impeller emit 4 hotspots which exit the fan at a wider angle. They are fine for evacuating air or exchanging air, but as far as setting it up on a table and aiming it at you, it is kind of worthless.

Most 120MM fans max out in the 110CFM range at about 0.4 to 0.5 amp draw.

The Silverstone fm121 is a 4 hotspot fan, but variable speed, 33 to 110CFM.

Delta makes some seriously powerful fans.

http://www.frozencpu.com/cat/l3/g36/c15/s562/list/p1/Fans-12_Volt_Fans-120mm_x_38mm_Fans-Page1.html

I purchased the 252CFM but my PWM speed controller could not slow it down enough to be useful. Thing draws 4 amps

http://www.frozencpu.com/products/i...-_Bare_Lead_PFB1212UHE-F00.html?tl=g36c15s562
Ridiculously loud and powerful at 12+ volts.

My interior circulation fans are Vantec Tornados, in 80MM and 92MM. I wish they made a 120MM version.
These do have the steering vanes and emit a narrow column of air which moves across my whole van.

As I type the 92mm fan is being fed 4.5 volts and Aimed at my chest.
This fan whined on the PWM speed controller at slower speeds.
http://www.amazon.com/Vantec-Tornado-TD8038H-80x80x38mm-Performance/dp/B000234VZK

http://www.amazon.com/gp/product/B0...d_t=201&pf_rd_p=1944687682&pf_rd_i=B000234VZK

I use a voltage controller as a speed controller for these Vantec fans. No whining at reduced speeds.

http://www.amazon.com/CyberPower-CP..._sim_23_2?ie=UTF8&refRID=1BRE0MTMSKS2SKE7PPA7

I also have the 92Mm fan on a 2 inch spring clamp with a gooseneck to aim it exactly where most effective.

That was an older voltage limiter which I replaced with the product linked above.

Not sure what your expectations for air movement are, you might be better off with the larger diameter 12v endless breeze fan many here seem to like.

I really like this fan too:
http://www.amazon.com/Silverstone-P...1438146275&sr=1-1&keywords=silverstone+AP+182

180MM and 164CFM and much quieter than 120Mm fans. Built in speed control, and it also moves a column of air, not 4 hotspots at wide angles

Saw this more recent offering from silverstone.

http://www.amazon.com/SilverStone-T...1438146275&sr=1-2&keywords=silverstone+AP+182

I suspect is has 5 hot spots at wider angles.

Acquire the fan grilles for the larger Silverstones, one hit to the impeller might snap or crack a blade and make the fan useless. The Tornados and the Fm121 come with grilles.
The Delta Fan blades can chop off a fingertip.

SternWake · Jul 29, 2015

In terms of making your existing fan turn faster, the only option is a voltage booster, and at the speeds you want from that 140MM 65CFM fan, might be too much for the fan. The hub might overheat.

Better to get a more powerful fan.

But here is a voltage booster. You could bump up the voltage, and still use that pwm dimmer,

But better to get a more powerful fan.

http://www.amazon.com/Geeetech-Conv...id=1438151473&sr=8-1&keywords=voltage+booster

I have one of these. For under 4$ how could I not buy one?
I make surplus 12v computer fans hover at 24 to 28 volts. But the fan hubs get way too hot to expect any longevity at that rpm.