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Re: PowerTOP tool released; time to fix the wasted laptop power on fedora?



On Sun, 2007-05-13 at 23:38 +0200, Martin Sourada wrote:
> Martin Sourada wrote:
> > Martin Sourada wrote:
> >>
> >>
> >> Cool thing, just tried it on rawhide with the not-so-unexpected result 
> >> where the top is liferea and epiphany followed by usb, XOrg and 
> >> eth0.... But what I didn't expect was the power usage and count of 
> >> wakeups:
> >> Wakeups-from-idle per second :  413.0
> >> Power usage (ACPI estimate) :   1.1 W (2.4 hours left)
> >>
> >> 1.1 W? That is really low IMO... Really, really interesting. Hope this 
> >> tool helps to improve linux powersaving capabilities in the future. 
> >> Keep the good work :-)
> >>
> >> Martin
> >>
> > 
> > I looked once more at the power usage: 1.1W... is it OK? Shouldn't there 
> > be 11W? I have quite ordinal laptop with Intel Celeron M 420, I don't 
> > think such low power usage is possible on this... Any idea? And well, I 
> > have the 1.1 version of PowerTOP.
> > 
> > Thanks,
> > Martin
> > 
> 
> As kernel says:
> # cat /proc/acpi/battery/BAT1/state
> present:                 yes
> capacity state:          ok
> charging state:          discharging
> present rate:            1212 mA
> remaining capacity:      262 mAh
> present voltage:         13759 mV
> 
> the power usage should be around 16 W. Is it a bug in the PowerTOP, or is it 
> supposed to mean something different (currently it shows 1.2 W)?
> 

It looks to me like it is using "present rate" which would be 1.2A
forgetting that to calculate Watts you need to multiply the current(A)
by voltage (V). A more reasonable answer would be...

Power drain = 1.212A * 13.759V = 16.676W 

	Jon



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