Picture of Super easy battery powerd computer fan
This is a really easy thing to make out of a bunch of recycled stuff. I had a bunch of extra computer fans so i decided to get some use out of them. Take a look. Sorry if this is not original.

Step 1: Materials

Picture of Materials
A computer fan (the bigger it is the more air it pushes)
A switch
A 9v battery
A 9v battery clip (thanks to the instructable on how to recycle 9vs i made my own)
JoeP2119 days ago

Would it help to use a transformer to step up the current to 12v? I don't know how it would work because transformers only take AC current right? And it also would not increase the current (transformers are passive). So maybe to make it safer, you could connect 3v in series with the 9v?

You all do realize if it's a small fan u can just use USB pose a big fan will work two just will be slow
mrjubjub5 years ago
Okay, for one, don't do this ever again two, you are going to blow up the battery because you are using a 12 volt DC fan with a 9 volt battery. After a while, the battery will heat up and eventually (most likely) explode. i recommend against doing this! just use a 12 volt supply

If you run the 9V in series it is fine, use two 9V and run them in series rather than parralel. So esentially U get 18v rather 9v wich will give you enough Volts to cover the 12 needed for the fan.

No mrjubjub, It will be fine. I've made plenty of these. I can run a 24v motor with a 6v battery. Don't use A23s for this, the fan will drain it in under 2 hours.
Say that to the 3 exploded batteries I have from when I did this. The only good thing I got out of it was a manufacturer's coupon for replacement batteries.
i dont think it will blow up, just turn the fan real slowly, and mabye mess up the motor? it would be diffrent if it was anything other than a motor. of course i could be wrong
all it will do is make it run slowly. you could se a 23A or similar 12v battery.
GauravC11 year ago

My cooler fan has three wires black, yellow and green . Black is confirm but wt bout other two >>>> Which one should i use GREEN OR YELLOW?????

jli54 years ago
Hi, I don't understand this step very well because I have never played around with a switch.
How did u attach the switch? Just cut half way between the red wire (which is connected to the fan and the battery) and just insert the switch in the middle?

Also, what kind of switch is the one in the picture? What kinds of switches are the smallest?

Thanks for the great guide!
kkitchell jli52 years ago
well either cut the wire or add more wire to it. The switch should either be attached to wires by a screw or soldering. Which of course you probably know it opens the circuit.
acurrie23 years ago
hello ,
im lost . im doing a thing for a solar project and needed 2 fans one to bring air in and the other for pushing the air out . i picked up a fan it has a double fans, it comes with black , red, blue and brown.
my questions is how to i find out what is the (-) and (+) . clearly there is 2 (-) and 2 (+) but can i hook it all to one battery or should i get two batterys one for each fan?also if its a 12 v dc what size battery should i use to get more then just a couple of hours ?

hi, does your fan have a sticker on it? it should. all my computer fans. look closely on the sticker, it should tell you the polarity. like,

+:Red, -:Black

or something like that(im looking at a computer fan for a windows XP here :P
jordomaller4 years ago
what if you use a potentiometer to regulate thespeed it has a resistor or something would that keep it from blowing up?
dragontirex4 years ago
if you use an good battery it will run few hours :d
Danny_Payne6 years ago
what is the blue one for?? temp??
RPM sensor
What are the extra wires (I.E. the blue wire) mentioned for?
Two cables = just power
Three cables = Power + speed sensing
Four Cables = Power +speed sensing + PWM control
meh3016 years ago
Can you please help? My fan is 12v and it does not go at full speed and I NEED it to go full speed.
use a 23A or similar 12v battery. and a 23A battery is smaller than an AA, so it will take up less space.
fwjs28 meh3016 years ago
add another battery 9v+1.5v(AA batery)+1.5v=12v
geekdude fwjs285 years ago
no two aa batteries
BOHUNTER085 years ago
How long can the fan run on a 9v? Could you use a bigger battery for longer use... say a week non-stop?
it only runs foir around 15 mins i have the same fan normally if im red hot ill run about 48v through it
grow box?
MT-LB5 years ago
the sealed lead-acid batteries from battery backup systems are good for this.
éolien6 years ago
Hey, great idea! Everything's simple and easy. thank you. congrats!
Dunkm1n6 years ago
Were you at all able to determine the RPMs of the fan, cus I was looking at adding some 9v powered fan to a cooling mat I was working on and wanted to know if a 9v would be enough for 2 or just one (as on paper the math comes out to 2 fans at 2500rpm)