12V fan operation at 8V [OT]

[D. Schouten]

Hi,

It won't degrade the fan's limetime. I talked to
a Sunon (=fan manufacturer) engineer once, discussing
this topic for a high volume (>2k pro year) product of us.
In some cases it will even extend it's lifetime.

However due to certain tolerances both electrical and
mechanical, it's advisable to give the fan some kind
of 'kickstart' at it's nominal voltage before decreasing
the voltage to a lower level. This way you're sure that
that the fans starts spinning properly.

In our application we had to decrease the fan voltage
from 12V down to 9V for acoustical reasons (hmm, sounds
like a recent thread :). Also the fan voltage carries
a 3Vtt ripple.
No broken fan detected up to now.

Bye,

Daniel...



> Sometimes it is usefull to cool circuitry with fans.
> Most of them operate with 12V (at least the smaller ones),
> most of them now have electronic steering (commutation sp?),
> and I assume that pretty flat dc voltage is expected by
> the fan designers, because they are used with switched power
> supplys. 
> 
> Now the question:
> 
> Will it be harmfull for these guys to run at a lower
> voltage, given that the rotor is still spinning?
> Will large ripples <12V be harmless?
> 
> Will it limit lifetime?
> 
> I'd like to save a wire or two, and have nominal 8V...
> 
> m.c.
> 
> 
>