Minutes of Power in 9.1.0 meeting

[david at lang.hm]

On Mon, 15 Dec 2008, John Gilmore wrote:

>> On a different note, one test we might think about running is the
>> closest thing the industry has to a "standard" battery life test.  It's
>> specified on a lot of the netbook specs.
>>
>> It's defined here: http://it.jeita.or.jp/mobile/e/index.html
>>
>> However, I'm also seeing that a lot of vendors are choosing not to use
>> this test because it generally results in a number higher than what the
>> typical user will actually get.
>
> I looked it over.  Companies report the average of two measurements:
> The hours of power available when the machine is dialed down to
> minimum power, screen at its very dimmest (reflective mode for us),
> doing nothing, everything disabled.  And the other measurement is when
> the system is playing back an MPEG movie, in a small window and with
> relatively standard OS and display settings.  (We can't do this out of
> the box, but we could install an MPEG codec for the test, and run it
> that way.  Or transcode their test movie to Ogg Theora and try that
> for simplified release testing, until we have to report an official
> number using MPEG.)
>
> It would be useful for us to measure and improve the numbers in
> both of those modes -- but the average will be highly misleading to
> everyone.  Still, it would provide a comparison to netbooks and other
> computers.
>
> It would be nice if our runtime in the minimum power mode could in
> 9.1.0 be almost equal to our "lid-closed suspend time", which I
> measured in #7879 to be 8 hours with mesh/wifi chip on, and 44+ hours
> with the mesh/wifi off.  Actually, it won't be that good, because the
> test requires that the screen remain on (perhaps consuming 0.5W),
> though the reflective screen means we can turn off the backlight.  So
> perhaps we'll get 16 to 20 hours in that mode.  If so, averaging with
> perhaps 2 to 4 hours of active runtime, for a total "standard" number
> of about 10 to 12 hours would still be pretty good by comparison to
> typical netbook products.

as-is you are pretty good. I used the XO to follow presentation slides 
recently. with wifi and the backlight off I went from 9-5 and showed a bit 
more than half the battery life left (not a lot of activity, just moving 
the slides periodicly, but never idle enough to let it turn off the 
screen). so your 16 or so hours looks pretty reasonable.

David Lang