PC case fan to run on batteries?

Sure, but you'd need to have enough voltage, which would be 12V. I believe that AAA and AA batteries are 1.5V each, so you'd need 8 of those.

Just have the positive to negative ends in sequence and have the wires from the fan going to the start and end of the battery chain.
 
how long do you think 8 of those batteries would be able to supply power to the fan for?
 
I really wouldn't know off hand. My guess is that the batteries would be drained within a few days of constant use, but that would depend on what type of battery you were using. Alkalines would probably go first, but if you used NiCd or NiMH, you'd have a longer go.
 
wow, its longer than i was expecting, i was thinking of somthing in the range of about 10 mins.

Also, i was wondering about extending the cables on the fans, can any cable do for extending it? and to connect more cbale do i just get tie the metal together?
 
You need to try and ascertain the mAh rate of the fan.
That is the amount of current which will flow through the fan every hour.
If the rate is in Ah you will need to multiply by a thousand, I think, to get the mAh rate.

some site I found said:
Simply put, mAh is the amount of electrical current a battery can put out for a certain amount of time. For example, a battery with a 1000 mAh rating could last about an hour (depending on how many of the camera's features are being run at the same time) and a battery with a 500 mAh rating will last half as long. The higher the mAh number the longer the output.
Click to expand...

Every battery states the amount of mAh it will provide.
Devide one by the other and you should get the time it will take the fan to drain the batteries.
 
Some decent NiMHs would be my choice.
Literally the first return on a search on ebay....

eBay.co.uk: 2600 mAh AA 4x Rechargeable NiMH Batteries 2600mah (item 120003494043 end time 05-Jul-06 22:00:00 BST)

As for the cable, its low current so you cant go too wrong. Just get something of similar thickness to the usual cables for fans. Specs wont be too important. And for sticking them together; you should solder them (I made a monitor power supply once from a PSU, worked fine until one wire came lose because I hadn't soldered yet) You will be OK with some heatshrink tube from B&Q or Halfords if you have'nt got a soldering iron/gun.

Your biggest problem will be wiring the batteries to get 12v. You will obviously need to charge them or buy new batteries and wire them up every time they run out. I once got some little cases from ebay which hold 4 baterries making 6v. You can pop them out when you need to and charge or replace them. Ive got some spare if you want some. I needed one and had to buy 8! I will have to check they were making 6v, I think they were because it was to power a RC receiver and servo for a remote control car I built.

A quick check on my fans. A little celeron fan ive got says 0.14A and an 80mm led fan also says 0.14a (i think the leds are powered by the fan spinning, ie you can spin it with your fingers and it will glow)
Thats 18h on a 2600mah battery.
 
hmm, are led fans with 4 wires ones that get power to power the led's from the power supply, and led fans with 2 wires ones that get the led's powerd by the movement?

also strangely enough, 2 of my led fans in my computer dont appear to be working properly, they spin ok, but 2 leds on one fan and 1 on the other aint working :s
 
Willz said:
hmm, are led fans with 4 wires ones that get power to power the led's from the power supply, and led fans with 2 wires ones that get the led's powerd by the movement?
Click to expand...

Most, if not all fans are 12v. The molex connector has 2 ground leads, a 5v lead and a 12v lead. The fan will only use the 12v and the ground next to the 12v. Ive never come across a fan with 4 leads. Some have 3, one is used to calculate the rate the fan is spinning. If it appears to have 4 leads might it be a connector which also has a giving plug? ie a male end as well as the female end (which draws power?) wow thats hard to explain without pictures!

Here is a quick reference
Drive Power Connectors
 
ah i noticed hey have 3 not 4, anyway on the cd holder build into my desk,i cut the holders so that they could fit 3 fans in, i have 2 fans on the cd holder were i cut so they could fit, and one fan i cut the fram around it off and stuch it onto the bottom.

see picture below, probs the wirdest thing you seen on a desk :p

http://img.photobucket.com/albums/v319/thehub/Desk-messy-fan.jpg
http://img.photobucket.com/albums/v319/thehub/Nightlights.jpg

One in light one in night, you see i wanted to run these 3 off batteries as the wires are all over the place, there going through the back of the case now, i got put off the diea of using battaries when i realised i would need about 24 batteries :p
 
You could still use 8 batteries. They would only last 1/3 of the time though as opposed to having 1 fan connected.

I think maplin to small 12v batteries. Not checked though.
 
wall transformer, bit costly aint it?

Yea the desk fans are to keep me cool, i cant be bothered plugging them bk into my computer tho.
 
No, transforemers aren't expensive at all. Those are the little (or big, depending on how you see it) black boxes that are on the power wires for speakers and such. You can buy ones with molex connectors already on them or I can tell you how to do it.
Safety First
If you were to get that, cut off the connector, strip the wires, and connect it to the 12 V wires on a molex connector then you have it.
 
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