how to connect DC fans to 5 volts ?

[space12]

hi,

i'm trying to make, laptop cooling pad as own.
hope it will help many members here,

my concept - i want to connect 2/3 DC fans(axial box fans, generally finds in computer cabinet) & through USB connector, i want to join it to laptop.for a cooling purpose.

but, now i am simply using 1 fan to 5 v usb right now.(i had tried 2 fans at one connection but another fan goes slow, so not confident about this experiment)

can you guys help me fast.

Some Points to Consider - fans which are going to connect 5 v USB connection should not Exceed 500mA. (heard that USB should not drawn more power than it. & should not be hectic to laptop battery but still very effect)

please explain here in detail.

 

[millwright]

Actually if you put a 600mA fan on that 500mA buss, the USB bus will put out 600mA.
Just not for long.

For devices of more than 500mA you need a powered hub.
Power sources have no way of limiting themselves, only the load can control load.


500ma = .5 amps

Not sure what you want to know, but here are some fan amps

I grabed 4 random fans from the shelf

3 are 92 mm
.15 or 150mA
.30 or 300mA
.28 or 280mA

Then an old sunon 80mm @ .16 or160mA probably about a 1500 RPM fan.

I also have a fast 80mm 3200RPM @.32amps or 320mA

 

[millwright]

You probably want 1200 RPM fans, or less, as they draw less power, and are quiet.

 

[space12]

Hello Millwright,

ok, lets assume we were choose fans Amps/type as per Laptop cooling need/specification,
but how to make connection in between them ? (wiring in between fans) &

how to control them (i doesn't mean each fan should have separate controller but at last one Or have to make such provision that after selecting same amps fans they should run same)

just have a look on some cooling pads which have such utility, it may get some idea about the same(connection is series or parallel)

Actually if you put a 600mA fan on that 500mA buss, the USB bus will put out 600mA.
Just not for long.

For devices of more than 500mA you need a powered hub.
Power sources have no way of limiting themselves, only the load can control load.


500ma = .5 amps

Not sure what you want to know, but here are some fan amps

I grabed 4 random fans from the shelf

3 are 92 mm
.15 or 150mA
.30 or 300mA
.28 or 280mA

Then an old sunon 80mm @ .16 or160mA probably about a 1500 RPM fan.

I also have a fast 80mm 3200RPM @.32amps or 320mA

 

[millwright]

If you get 3 identical fans they ill all run the same speed, but the are 12volt fans, aren't they?
You won't want a speed controller, that reduces voltage further.
5 volts doesn't give you much room between there and 0.

Unless you want a big blob of wires. plugs, and speed controllers, I.d just solder the 3 fans wires together, in parallel, then solder it to you USB plug.
Shrink tube the solder joints.
Hot glue works too.