N900 battery duration

Aniello Del Sorbo wrote:
> An N8x0 in offline mode (idle) consumes much less energy in a night
> than its minutes-long start up.

Does somebody have any data on this?

--
Tuomas

On Tue, Nov 10, 2009 at 8:22 AM, Tuomas Kulve <tuomas@kulve.fi> wrote:
> Eero Tamminen wrote:
>> (You may remember that e.g. N8x0 use less battery if it's put to
>> offline-mode instead of being shut down for the night.)
>
> How's that possible? Offline mode shuts down the wireless stuff but
> still runs the cpu. And, afaik, shutting down the device shuts down the
> cpu etc. as well (not sure what happens if you have alarms there). Do
> you happen to have a pointer to some old discussions or wherever this
> has been explained?
>
> --
> Tuomas

This is just one of many myths regarding the tablets. What is true is
that if you turn your tablet off and on *many* times during a day, you
will experience shorter battery duration than if you just put it to
sleep. The reasons are as stated: when starting up and shutting down
you are running the machine at full blast for a significant length of
time, which rarely happens otherwise. However, if you only turn it on
once or twice a day, your battery will last many more days if you shut
it down than if you leave it on, even at maximum power savings.

Mark

On Tuesday 10 November 2009 16:31:47 Tuomas Kulve wrote:
> Aniello Del Sorbo wrote:
> > An N8x0 in offline mode (idle) consumes much less energy in a night
> > than its minutes-long start up.
>
> Does somebody have any data on this?

Some interesting data:

http://www.slideshare.net/igor_stoppa_nokia/power-management-for-the-nokia-internet-tablets

Also, what is often not discussed is that is seems a reboot affects the power
meter itself (either via some battery chemistry effect or some other
mysterious way) so you can get inconsistent readings - I have theoreticeally
lost ~30% of capacity after a reboot (which is not physically possible
without melting) and on another occasion I ended up with a fuller battery
than I started the reboot with (which is also nothing short of impossible).

On Tuesday 10 November 2009 16:31:47 Tuomas Kulve wrote:
> Aniello Del Sorbo wrote:
> > An N8x0 in offline mode (idle) consumes much less energy in a night
> > than its minutes-long start up.
>
> Does somebody have any data on this?

Some interesting data:

http://www.slideshare.net/igor_stoppa_nokia/power-management-for-the-nokia-internet-tablets

Also, what is often not discussed is that is seems a reboot affects the power
meter itself (either via some battery chemistry effect or some other
mysterious way) so you can get inconsistent readings - I have theoreticeally
lost ~30% of capacity after a reboot (which is not physically possible
without melting) and on another occasion I ended up with a fuller battery
than I started the reboot with (which is also nothing short of impossible).

Igor.Stoppa@nokia.com wrote:
> Tuomas Kulve wrote:
>
>> Igor.Stoppa@nokia.com wrote:
>
>>> Running the test with a headset plugged in would get rid of the offset.
>
>> Offset? Is that something that affects the MP3 in a different manner
>> than Ogg?
>
> It should be the same, but since you are interested in the power
> consumption of the decoding activity - if i understood correctly -
> then you get an unknown term, which can also have 2nd order
> effects due to the different timing and choices that both cpuidle
> and cpufreq could make.
>
> iow, if you have time, it might be interesting to run the test again
> with an headset.

I repeated three runs with ffvorbis and got a bit over three hours more
battery life with the headset connected compared to my earlier ffvorbis
tests without the headset.

--
Tuomas

On Tue, 10 Nov 2009, Tuomas Kulve wrote:

> Aniello Del Sorbo wrote:
>> An N8x0 in offline mode (idle) consumes much less energy in a night
>> than its minutes-long start up.
>
> Does somebody have any data on this?

Here is some data:

http://talk.maemo.org/showpost.php?p=361648&postcount=23

Abstract: The often repeated claim that a reboot cycle wastes a lot of
battery is incorrect.


--
Matan.

2009/11/11 Matan Ziv-Av <matan@svgalib.org>:
> On Tue, 10 Nov 2009, Tuomas Kulve wrote:
>
>> Aniello Del Sorbo wrote:
>>>
>>> An N8x0 in offline mode (idle) consumes much less energy in a night
>>> than its minutes-long start up.
>>
>> Does somebody have any data on this?
>
> Here is some data:
>
> http://talk.maemo.org/showpost.php?p=361648&postcount=23
>
> Abstract: The often repeated claim that a reboot cycle wastes a lot of
> battery is incorrect.
>

To have a fair comparison you should now check the battery-status
before going to sleep and when waking up again so to compare how much
battery went down in one night.

Interesting results nonetheless.
Thanks!

--
anidel

2009/11/10 Tuomas Kulve <tuomas@kulve.fi>:
> Aniello Del Sorbo wrote:
>> An N8x0 in offline mode (idle) consumes much less energy in a night
>> than its minutes-long start up.
>
> Does somebody have any data on this?
>

I don't, but I do remember an e-mail or thread somewhere long ago about this.
I was reporting it by memory.

--
anidel
Sent from London, Eng, United Kingdom

Matan Ziv-Av wrote:
> Here is some data:
>
> http://talk.maemo.org/showpost.php?p=361648&postcount=23
>
> Abstract: The often repeated claim that a reboot cycle wastes a lot of
> battery is incorrect.
>

Hmm, you proved you can drain battery in 44 reboot cycles in 2 and half
hours. To me it says reboot wastes a lot of battery :-) You can play
video or surf the web longer than 2.5 hours. In fact there is not many
things that could drain battery faster than reboots, is it?

I have posted my findings with one spare N810 to that thread. I got like
30 days with N810 sitting completely idle. That would roughly mean one
reboot is 16 hours of standby (with no wi-fi).

Frantisek

2009/11/11 Frantisek Dufka <dufkaf@seznam.cz>:
> Matan Ziv-Av wrote:
>> Here is some data:
>>
>> http://talk.maemo.org/showpost.php?p=361648&postcount=23
>>
>> Abstract: The often repeated claim that a reboot cycle wastes a lot of
>> battery is incorrect.
>>
>
> Hmm, you proved you can drain battery in 44 reboot cycles in 2 and half
> hours. To me it says reboot wastes a lot of battery :-) You can play
> video or surf the web longer than 2.5 hours. In fact there is not many
> things that could drain battery faster than reboots, is it?
>
> I have posted my findings with one spare N810 to that thread. I got like
> 30 days with N810 sitting completely idle. That would roughly mean one
> reboot is 16 hours of standby (with no wi-fi).
>
> Frantisek
>

The issue was (abstract) if a reboot would consume more energy than a
night-long idle.

If you swap "reboots" with "nights" and assume "night consumption <=
reboot consumption" then you should be able
to squeeze up to 44 nights out of a charged battery.

--
anidel
Sent from London, Eng, United Kingdom