[maemo-developers] [maemo-developers] Re: Measuring power consumption of 770

[From: Igor Stoppa]

Interesting ... frankly nothing new to me, but it is a good start point
that proves how it is possible to have good performances even with low
power devices.

Next week i probably won't be able to reply to anything, however soonish
Maemo designing/coding guidelines will be available, and i hope we'll
have some discussion about battery-friendly drivers/applications.

igor

On Wed, 2006-03-29 at 19:40 -0500, ext Larry Battraw wrote:
>   Ok Igor, you finally motivated me to do some measurements :-)   All
> measurements were done with a .1 ohm resistor (measured as .0924 ohms
> using the 4-wire method) and a HP 3456A 6.5 digit voltmeter.  The
> meter was set to the slowest (most accurate) sampling rate, performing
> the calculations on-the-fly for the Ohm's law derived current.  I did
> _not_ measure battery voltage, so wattage calculations are not
> possible.  This shouldn't be a big deal as the current will give a
> good indication of what the device is doing at the time.  I've
> attached a CSV file of the spreadsheet for results.  I tried to hit
> most of the use cases people might be interested in, and everything is
> pretty impressive except for leaving MP3 files paused in the media
> player, which consumes over 10 times the normal current while
> sleeping.
> 
> Larry
> 
> On 3/29/06, Igor Stoppa <igor.stoppa at nokia.com> wrote:
> > Hi,
> >
> > On Tue, 2006-03-21 at 11:31 -0500, ext Larry Battraw wrote:
> > >   I would advocate building a dummy battery out of a piece of
> > > wood/plastic with a small piece of copper clad board (split into three
> > > pads) to act as the contacts of the battery.  You can then run wires
> > > from those to the real battery, passing it through whatever
> > > resistor/sensing equipment you want.  As soon as you try measuring
> > > what goes into the DC jack you're then including whatever losses
> > > incurred by the DC-DC conversion from 5V to whatever used internally,
> > > as well as issues around having it potentially trying to charge the
> > > battery at the same time you're measuring.  That, and Igor as much as
> > > said that things could behave differently based on whether it detects
> > > wall/DC power vs. battery power alone.  Honestly, at this point you
> > > probably could have built a couple rigs for measuring power from the
> > > battery in all the time that has been spent discussing it.  :-)
> > >
> > > Larry
> > >
> > > On 3/21/06, Frantisek Dufka <dufkaf at seznam.cz> wrote:
> > >
> > > > Well I was not thinking about measuring at the mains plug. I was
> > > > thinking about measuring at the n770 side (5V?) because it is a bit
> > > > easier then opening the device and messing with battery pins.
> > > >
> > > > Frantisek
> > > _______________________________________________
> > > maemo-developers mailing list
> > > maemo-developers at maemo.org
> > > https://maemo.org/mailman/listinfo/maemo-developers
> >
> > did anybody produce anything?
> >
> > I was hoping that the discussion would bring some interest to the
> > fabulous world of power management also amongst other developers ...
> >
> > --
> > Cheers,
> >            Igor
> >
> > Igor Stoppa (Nokia M - OSSO / Tampere)
> >
-- 
Cheers,
           Igor

Igor Stoppa (Nokia M - OSSO / Tampere)