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N900 battery duration

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Igor.Stoppa at nokia

Nov 7, 2009, 4:23 AM

Post #51 of 70 (283 views)
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RE: N900 battery duration [In reply to]

Jean-Christian de Rivaz wrote:

> But how the speaker protection algorythms can make a difference between
> ffvorbis and libvorbis since the output should be exactly the same ?

both cpuidle and cpufreq target the next state based on activity and
idleness thresholds.

if the algos add just enough to cross any limit that otherwise would not be passed, they can
have quite an influence.

especially if the performance of the 2 decoders is isgnificantly different.

Think about a thrshold-based tax system, if you want a (loose) analogy.

igor
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eero.tamminen at nokia

Nov 10, 2009, 5:56 AM

Post #52 of 70 (255 views)
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Re: N900 battery duration [In reply to]

Hi,

ext Tuomas Kulve wrote:
> Tuomas Kulve wrote:
>> Igor.Stoppa[at]nokia.com wrote:
>>> There is a bug in the cellmo SW related to absence of SIM: the current is higher when the SIM is not in.
>>> So in real life use case (i assume people who will buy it will actually use it as a phone) the use time will be longer.
>> I guess I need to do more testing then :)
>>
>> Although I'm not sure how to accomplish that as I need my SIM for the
>> daily use..
>
> The previous test was without a SIM card. The device was very idle and
> run for 93.75 hours (with a guessed few hour error marginal).
>
> After charging the battery I inserted the SIM card, rebooted and started
> a new test.

Why reboot?

I would expect most people just to charge without shutting down
the device.

(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.)

> I received two calls (hung up immediately), I received two
> SMS messages and sent one, and the notifier led was blinking for 45 mins
> at one point. Otherwise the device was idle and run for 93.62 hours. So
> pretty close to the test without a SIM card.
>
> I have a small shell script running there that writes a log every 60
> seconds. After writing the log it runs the "sync" command and starts the
> loop again. I'm assuming it doesn't affect the total run time much in an
> otherwise idle device.

- Eero
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dieter at plaetinck

Nov 10, 2009, 6:06 AM

Post #53 of 70 (255 views)
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Re: N900 battery duration [In reply to]

On Tue, 10 Nov 2009 15:56:13 +0200
Eero Tamminen <eero.tamminen[at]nokia.com> wrote:

> I would expect most people just to charge without shutting down
> the device.
>
> (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.)

heh? why is that?

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anidel at gmail

Nov 10, 2009, 6:13 AM

Post #54 of 70 (255 views)
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Re: N900 battery duration [In reply to]

2009/11/10 Dieter Plaetinck <dieter[at]plaetinck.be>:
> On Tue, 10 Nov 2009 15:56:13 +0200
> Eero Tamminen <eero.tamminen[at]nokia.com> wrote:
>
>
>> I would expect most people just to charge without shutting down
>> the device.
>>
>> (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.)
>
> heh? why is that?
>

Well in the case of the N8x0 when booting up the screen brightness was
up to its maximum.
When booting up all the tablets chips and fishes uses maximum energy
until the PM kicks in and
takes control of everything.
This consumes A LOT of energy.
An N8x0 in offline mode (idle) consumes much less energy in a night
than its minutes-long start up.
--
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tuomas at kulve

Nov 10, 2009, 7:22 AM

Post #55 of 70 (255 views)
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Re: N900 battery duration [In reply to]

Eero Tamminen wrote:
>> The previous test was without a SIM card. The device was very idle and
>> run for 93.75 hours (with a guessed few hour error marginal).
>>
>> After charging the battery I inserted the SIM card, rebooted and started
>> a new test.
>
> Why reboot?

So that I know the start scenario is the same. Not rebooting and doing
several tests in a row easily leads to increased memory consumption,
dying processes and weird behaviour.

> I would expect most people just to charge without shutting down
> the device.

Of course. I'm not booting the device in normal usage.

> (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
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tuomas at kulve

Nov 10, 2009, 7:31 AM

Post #56 of 70 (255 views)
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Re: N900 battery duration [In reply to]

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?

--
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wolfmane at gmail

Nov 10, 2009, 7:55 AM

Post #57 of 70 (255 views)
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Re: N900 battery duration [In reply to]

On Tue, Nov 10, 2009 at 8:22 AM, Tuomas Kulve <tuomas[at]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
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maemo at csipa

Nov 10, 2009, 8:37 AM

Post #58 of 70 (254 views)
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Re: N900 battery duration [In reply to]

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).
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tuomas at kulve

Nov 10, 2009, 10:34 AM

Post #59 of 70 (254 views)
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Re: N900 battery duration [In reply to]

Igor.Stoppa[at]nokia.com wrote:
> Tuomas Kulve wrote:
>
>> Igor.Stoppa[at]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.

--
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matan at svgalib

Nov 11, 2009, 1:58 AM

Post #60 of 70 (245 views)
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Re: N900 battery duration [In reply to]

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.
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anidel at gmail

Nov 11, 2009, 2:37 AM

Post #61 of 70 (235 views)
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Re: N900 battery duration [In reply to]

2009/11/11 Matan Ziv-Av <matan[at]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!

--
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anidel at gmail

Nov 11, 2009, 2:37 AM

Post #62 of 70 (235 views)
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Re: N900 battery duration [In reply to]

2009/11/10 Tuomas Kulve <tuomas[at]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
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dufkaf at seznam

Nov 11, 2009, 4:04 AM

Post #63 of 70 (235 views)
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Re: N900 battery duration [In reply to]

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

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anidel at gmail

Nov 11, 2009, 4:15 AM

Post #64 of 70 (235 views)
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Re: N900 battery duration [In reply to]

2009/11/11 Frantisek Dufka <dufkaf[at]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
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tuomas at kulve

Nov 11, 2009, 4:32 AM

Post #65 of 70 (229 views)
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Re: N900 battery duration [In reply to]

Frantisek Dufka wrote:
> 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).

30 days. That's quite nice. Any idea why n900 gets only to 4 days then?
What makes the difference so big? I didn't run it on offline mode though.

--
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dufkaf at seznam

Nov 11, 2009, 4:58 AM

Post #66 of 70 (229 views)
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Re: N900 battery duration [In reply to]

Aniello Del Sorbo wrote:
>
> The issue was (abstract) if a reboot would consume more energy than a
> night-long idle.

As I said - by Matan's equation in the forum post, one
reboot is 16 hours of standby. So at least with wi-fi off, keeping it
idle looks better. I was thinking about testing with wi-fi but my router
cannot keep connection for so long so it would be a bit mor complex than
just keeping it in the drawer.

> you should be able
> to squeeze up to 44 nights out of a charged battery.

I guess with 30 full days I could do 60 nights ;-) But I somehow need to
keep it powered off during daytime. Maybe I could shut it down in the
morning and boot it in the evening to save power ;-)

Frantisek

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anidel at gmail

Nov 11, 2009, 5:03 AM

Post #67 of 70 (229 views)
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Re: N900 battery duration [In reply to]

2009/11/11 Frantisek Dufka <dufkaf[at]seznam.cz>:
> Aniello Del Sorbo wrote:
>>
>> The issue was (abstract) if a reboot would consume more energy than a
>> night-long idle.
>
> As I said - by Matan's equation in the forum post, one
> reboot is 16 hours of standby. So at least with wi-fi off, keeping it
> idle looks better. I was thinking about testing with wi-fi but my router
> cannot keep connection for so long so it would be a bit mor complex than
> just keeping it in the drawer.
>
>> you should be able
>> to squeeze up to 44 nights out of a charged battery.
>
>
> I guess with 30 full days I could do 60 nights ;-) But I somehow need to
> keep it powered off during daytime. Maybe I could shut it down in the
> morning and boot it in the evening to save power ;-)
>
> Frantisek
>

Yeah, that's true. So far it looks like a reboot is mostly equal to a
night-long idle consumption.
To me at least. 44 reboots and 60 nights, considering a difference in
how old a battery is, could
very well be the case. I also take a bit into account battery heat
dissipation (in the case of 44 consecutive reboot).

So, I would guess that leaving it on in offline is better than turning
it off and than on during the night (it's faster to
switch between offline/online than actually rebooting).
But rebooting ensures and memory leak gets a workaround. oh well..
--
anidel
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matan at svgalib

Nov 11, 2009, 5:07 AM

Post #68 of 70 (229 views)
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Re: N900 battery duration [In reply to]

On Wed, 11 Nov 2009, Frantisek Dufka wrote:

> 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 cannot play video for 2.5 hours on my almost 2 years old N810. I can
hardly read an ebook for this long.

In addition I have dual boot, including 30s delay. During this delay
screen is on maximum brightness, and I don't know which power saving
features are enabled, so without this delay, a few more reboots might
be possible.

> 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).

This must be very atypical. In similar tests on a new N800 I never even
managed two weeks (in offline mode).

The main reason I suggest turning off when the device is not going to be
used for long periods (such as a night sleep) is the non-slim chance
that something might cause break power saving (metalayer-crawler, router
incompatible with power saving, forgetting to disconnect bluetooth,
etc.) and you wake up to see a dead device.

--
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dufkaf at seznam

Nov 11, 2009, 5:43 AM

Post #69 of 70 (229 views)
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Re: N900 battery duration [In reply to]

Matan Ziv-Av wrote:
> I cannot play video for 2.5 hours on my almost 2 years old N810. I can
> hardly read an ebook for this long.
>
> In addition I have dual boot, including 30s delay. During this delay
> screen is on maximum brightness, and I don't know which power saving
> features are enabled, so without this delay, a few more reboots might
> be possible.

Good points.

>
>> 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).
>
> This must be very atypical. In similar tests on a new N800 I never even
> managed two weeks (in offline mode).

N800 is worse, see Igor's post here
http://lists.maemo.org/pipermail/maemo-users/2008-February/009409.html

My numbers is from my own measurements I did later. The extra N810 was
new at that time.

>
> The main reason I suggest turning off when the device is not going to be
> used for long periods (such as a night sleep) is the non-slim chance
> that something might cause break power saving (metalayer-crawler, router
> incompatible with power saving, forgetting to disconnect bluetooth,
> etc.) and you wake up to see a dead device.

Yes, definitely.

I was trying to solve this by send SIGSTOP to offending processes
(browser in particular) when keyboard and screen is locked and it
somehow worked. It is relatively easy to do it as powerlaunch script.
With nice UI that would allow to picks up offenders by monitoring CPU
usage this could be useful tool for poor man's suspend. Basically by
locking screen and keys every process except few critical onces could be
stopped and later resumed (SIGSTOP,SIGCONT) when device is unlocked.
Would not solve keeping audio open etc.

Frantisek
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wolfmane at gmail

Nov 11, 2009, 8:38 AM

Post #70 of 70 (221 views)
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Re: N900 battery duration [In reply to]

On Wed, Nov 11, 2009 at 5:58 AM, Frantisek Dufka <dufkaf[at]seznam.cz> wrote:
> Aniello Del Sorbo wrote:
>>
>> The issue was (abstract) if a reboot would consume more energy than a
>> night-long idle.
>
> As I said - by Matan's equation in the forum post, one
> reboot is 16 hours of standby. So at least with wi-fi off, keeping it
> idle looks better. I was thinking about testing with wi-fi but my router
> cannot keep connection for so long so it would be a bit mor complex than
> just keeping it in the drawer.
>
>> you should be able
>> to squeeze up to 44 nights out of a charged battery.
>
>
> I guess with 30 full days I could do 60 nights ;-) But I somehow need to
> keep it powered off during daytime. Maybe I could shut it down in the
> morning and boot it in the evening to save power ;-)
>
> Frantisek
>

The absurdity knows know bounds. You're saying a battery will last
longer with a device turned on in sleep mode than it is even capable
keeping a charge sitting all by itself out of the device on a counter.
Give me a break. We're talking real-world usage here. If you actually
*use* the device, rather than just letting it sit idle doing nothing
(in which case why do you even own the thing?!?!?!), you're not going
to get anything like that kind of battery duration. I've tried putting
my N800 in offline & sleep mode at night, and never got more than 3
days out of it, even with very little usage during the day. If I turn
it off when I'm not using it and turn it on and back off 2-4 times a
day, I can get 1 to 2 weeks out of it. Even if the N810s are better,
there are too many variables to defend such outrageous claims,
especially if you (again) actually use the thing and install any apps
that run in the background.

Let's leave theory to the theorists and take a dose of reality, okay?

Mark
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