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Question about computer fans, volts, and amps.. [Archive] - DVD Talk Forum
 
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View Full Version : Question about computer fans, volts, and amps..


namrfumot
11-21-11, 04:55 PM
I need an DC adapter to power either 4 or 6 of these computer fans for a non-computer related project:

http://www.newegg.com/Product/Product.aspx?Item=N82E16811999199

I know to run at full power they need 12v, but to make them slightly quiter I've been running them at 9v. My question is how many milliamps do I need to fully power six of them at 9v?

X
11-21-11, 05:26 PM
You'd need to know the wattage (or amperage draw) they require at 9v. Even that number at 12v would help.

And remember, the amount they'll need will be greater at startup than once they're running.

Looks like it's 1.6A at 12v from the picture. So 4 or 6 times that would be a good number of amps to have available. Maybe 4 or 6 times (12/9)*1.6 would be best, but maybe they don't draw as much amperage at lower voltage? I don't know the answer to that.

namrfumot
11-21-11, 05:44 PM
I've looked everywhere for the wattage at 12v...even enermax's webpage doesn't list it!

Ok I found the stats on a similar 80mm model:

Numbers are for 12v...

Current (Ampere)
0.04 A (Max)

Input (Watt)
4.80

So now I'm confused about what amperage I would need to fully power 6 fans at 12v....

X
11-21-11, 06:02 PM
Look at the pictures Newegg has. It shows amperage.

namrfumot
11-21-11, 06:25 PM
Oh snap you were right X....1.6amps at 12v....so 6 times that is 9.6A or 9600mA? That seems like a HUGE number....

X
11-21-11, 08:05 PM
Well, 9.6 amps (9600mA) times the voltage is 115 watts. Much higher than you would expect. I think it's probably the max startup wattage that might be required and then it settles down. Turning them on in sequence could help lower the requirements.

namrfumot
11-21-11, 09:14 PM
X fwiw I'm powering them right now with a cheapo Radio Shack adapter. It's 9v and 800mA....the fans spin but not at full power. I'd need over 10x that amperage to get them to run at full 12v power?Electricity baffles me... :(

wmansir
11-21-11, 09:18 PM
1.6A seems very high for such a low power noise/airflow fan.

Take this for example, It's a basic fan that Newegg sells for $5 shipped :
CoolerMaster SAF-B82-E1
http://www.coolermaster-usa.com/product.php?product_id=2883

It's a faster fan, but it's specs show only 0.10A or 1.2W@12V.

X
11-21-11, 09:19 PM
Yeah, those fans seem extremely power hungry. I'd look for alternatives.

namrfumot
11-21-11, 09:25 PM
X...I just looked at the fan I have in hand...it says 0.2A. Nt sure why the pic at newegg says 1.6!

So to power 6 fans (at 12v) I'd need 1.2 amps...at 9v it'd prob be slightly less though.

wmansir
11-21-11, 09:46 PM
http://www.ecomastertek.com/fan_uc-8eb.php

Says its "0.16Ae". Pretty sure the 'e' is a typo.

X
11-21-11, 09:52 PM
Crappy picture!

namrfumot
11-21-11, 09:57 PM
So with that number in mind I'm gonna get an adapter like this:

http://www.amazon.com/Hosa-ACD477-100-240V-Voltage-Adaptor/dp/B000Z31G3M/ref=cm_cr_pr_product_top

it has more than enough amps to power the fans and I can switch between 5, 7.5, and 9 volts to find the speed/air flow I need.