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What is Best practice for Battery Longevity on N8X0?

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jholmblad at acadiasecurenets

Feb 13, 2008, 8:54 AM

Post #1 of 11 (1276 views)
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What is Best practice for Battery Longevity on N8X0?

All,

based on recent correspondence on this list I am beginning to wonder if
keeping the N800 or N810 plugged in to the charger will result in the
longest useful life of the battery.

Intuitively keeping the device plugged in seems to be the right thing to
do since it will then be fully charged when I have to disconnect the
charger in order to go somewhere with the device. Any thoughts from
Nokia battery experts on this list?

--

Best Regards,

John Holmblad

Acadia Secure Networks, LLC

* *

<mailto:jholmblad [at] verizon>

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igor.stoppa at nokia

Feb 13, 2008, 12:19 PM

Post #2 of 11 (1236 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Hi,
On Wed, 2008-02-13 at 11:54 -0500, ext John Holmblad wrote:
> All,
>
> based on recent correspondence on this list I am beginning to wonder if
> keeping the N800 or N810 plugged in to the charger will result in the
> longest useful life of the battery.
>
> Intuitively keeping the device plugged in seems to be the right thing to
> do since it will then be fully charged when I have to disconnect the
> charger in order to go somewhere with the device. Any thoughts from
> Nokia battery experts on this list?

I'm not really involved in putting the charge in but rather in making it
stay there as long as possible, however here are few comments:

- the charging is far from being passive, so having the charger plugged
in doesn't mean the it will be charging all the time, it depends on the
charging algorythm, which will stop charging when it thinks the full
charge has been reached; of course it will keep the battery topped, but
unless you leave your tablet unused for days in a row, it won't really
make a difference, as long as you have not installed some broken
application/daemon

- n800 and n810 have the same battery capacity, but due to few hw
bugfixes, the projected idle time is not the same (bear in mind that
this is much more than what is advertised since the advertisement takes
into account also possible variances in the components batches and
anyway it's unlikely that the tablet stays unused for so long ;)

n800: 18 days
n810: 27 days

The difference is huge in terms of time, but the measured current is
quite low, hence even small deltas have significant impact.

Note that this is measured with no connection/extra sw installed or
applications running.

--

Cheers, Igor

---

Igor Stoppa
Next Generation Software
Nokia Devices R&D - Helsinki
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dufkaf at seznam

Feb 14, 2008, 1:38 AM

Post #3 of 11 (1216 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Igor Stoppa wrote:
> - n800 and n810 have the same battery capacity, but due to few hw
> bugfixes, the projected idle time is not the same (bear in mind that
> this is much more than what is advertised since the advertisement takes
> into account also possible variances in the components batches and
> anyway it's unlikely that the tablet stays unused for so long ;)

I actually got one spare N810 (thanks Quim :-) so I hope I will make
similar tests with it until I find better use for it or I break my
primary one. If anyone here is interested in some specific test I can
run, let me know. I don't have any precise measuring tools so it must be
done in software. I think someone done something listenin to d-bus
events and reporting battery percentage. I plan to test at least
efficiency of mp3 playback with CPU/DSP at 330/220 vs 400/165.

>
> n800: 18 days
> n810: 27 days

Impressive, any details where the savings were done? Is this strictly HW
related and the n800 has same OS2008 version as N810?

>
> Note that this is measured with no connection/extra sw installed or
> applications running.
>
The default setting for new device is glowing blue led when device is in
standby, are those 27 days measured with glowing blue led? Do the LEDs
in N810 still eat CPU power when blinking?

Frantisek
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igor.stoppa at nokia

Feb 14, 2008, 1:50 AM

Post #4 of 11 (1217 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Hi,
On Thu, 2008-02-14 at 10:38 +0100, ext Frantisek Dufka wrote:
> Igor Stoppa wrote:
> > - n800 and n810 have the same battery capacity, but due to few hw
> > bugfixes, the projected idle time is not the same (bear in mind that
> > this is much more than what is advertised since the advertisement takes
> > into account also possible variances in the components batches and
> > anyway it's unlikely that the tablet stays unused for so long ;)
>
> I actually got one spare N810 (thanks Quim :-) so I hope I will make
> similar tests with it until I find better use for it or I break my
> primary one. If anyone here is interested in some specific test I can
> run, let me know. I don't have any precise measuring tools so it must be
> done in software. I think someone done something listenin to d-bus
> events and reporting battery percentage. I plan to test at least
> efficiency of mp3 playback with CPU/DSP at 330/220 vs 400/165.

cool

> > n800: 18 days
> > n810: 27 days
>
> Impressive, any details where the savings were done? Is this strictly HW
> related and the n800 has same OS2008 version as N810?

it's both hw and sw; the sw part is about fixing wrong settings in muxing,
pullup&pulldown and disabling voltage regulators when not in use or OMAP
is in retention.

> > Note that this is measured with no connection/extra sw installed or
> > applications running.
> >
> The default setting for new device is glowing blue led when device is in
> standby, are those 27 days measured with glowing blue led?

No, that's the wow effect :-D

> Do the LEDs
> in N810 still eat CPU power when blinking?

No, there is a dedicated, programmable chip, nickname NJoy, which takes
care of it. A similar one is in the keyboard controlled and provides
backlighting.

I posted some time ago a link to the public (and complete!) datasheet on
ITT, in the easter egg thread, iirc.

It's connected over i2c so it should be quite easy to play with it.

A nice experiment would be to write a userspace tool which can generate
the program sequence to dump to the njoy for obtaining user-defined
patterns.

--

Cheers, Igor

---

Igor Stoppa
Next Generation Software
Nokia Devices R&D - Helsinki
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dufkaf at seznam

Feb 14, 2008, 5:08 AM

Post #5 of 11 (1211 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Igor Stoppa wrote:
>>> n800: 18 days
>>> n810: 27 days
>> Impressive, any details where the savings were done? Is this strictly HW
>> related and the n800 has same OS2008 version as N810?
>
> it's both hw and sw; the sw part is about fixing wrong settings in muxing,
> pullup&pulldown and disabling voltage regulators when not in use or OMAP
> is in retention.

Just to confirm, these 18 days are already on N800 with OS2008 and with
those sw issues fixed?

>> Do the LEDs
>> in N810 still eat CPU power when blinking?
>
> No, there is a dedicated, programmable chip, nickname NJoy, which takes
> care of it. A similar one is in the keyboard controlled and provides
> backlighting.
>
> I posted some time ago a link to the public (and complete!) datasheet on
> ITT, in the easter egg thread, iirc.

Found it, thanks, here are the links

http://www.internettablettalk.com/forums/showthread.php?p=100358#post100358
http://www.internettablettalk.com/forums/showthread.php?p=100373#post100373

The page http://www.national.com/pf/LP/LP5521.html mentions also
"Comprehensive application tools are available, including command
compiler for easy LED sequence programming." but there is no download
link. One perhaps needs to contact them and this complier may not be
free (as beer).

Frantisek
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igor.stoppa at nokia

Feb 14, 2008, 6:17 AM

Post #6 of 11 (1211 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

On Thu, 2008-02-14 at 14:08 +0100, ext Frantisek Dufka wrote:
> Igor Stoppa wrote:
> >>> n800: 18 days
> >>> n810: 27 days
> >> Impressive, any details where the savings were done? Is this strictly HW
> >> related and the n800 has same OS2008 version as N810?
> >
> > it's both hw and sw; the sw part is about fixing wrong settings in muxing,
> > pullup&pulldown and disabling voltage regulators when not in use or OMAP
> > is in retention.
>
> Just to confirm, these 18 days are already on N800 with OS2008 and with
> those sw issues fixed?

I don't remember if i checked exactly the sw version that is public atm
but if it wasn't then it was close enough.

> >> Do the LEDs
> >> in N810 still eat CPU power when blinking?
> >
> > No, there is a dedicated, programmable chip, nickname NJoy, which takes
> > care of it. A similar one is in the keyboard controlled and provides
> > backlighting.
> >
> > I posted some time ago a link to the public (and complete!) datasheet on
> > ITT, in the easter egg thread, iirc.
>
> Found it, thanks, here are the links
>
> http://www.internettablettalk.com/forums/showthread.php?p=100358#post100358
> http://www.internettablettalk.com/forums/showthread.php?p=100373#post100373
>
> The page http://www.national.com/pf/LP/LP5521.html mentions also
> "Comprehensive application tools are available, including command
> compiler for easy LED sequence programming." but there is no download
> link. One perhaps needs to contact them and this complier may not be
> free (as beer).

Or one could write the compiler :-)
The language is not so rich

--

Cheers, Igor

---

Igor Stoppa
Next Generation Software
Nokia Devices R&D - Helsinki
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gmane at nmacleod

Feb 14, 2008, 6:01 PM

Post #7 of 11 (1205 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Igor Stoppa wrote:
> On Thu, 2008-02-14 at 14:08 +0100, ext Frantisek Dufka wrote:
>> Igor Stoppa wrote:
>>>>> n800: 18 days
>>>>> n810: 27 days
>>>> Impressive, any details where the savings were done? Is this strictly HW
>>>> related and the n800 has same OS2008 version as N810?
>>> it's both hw and sw; the sw part is about fixing wrong settings in muxing,
>>> pullup&pulldown and disabling voltage regulators when not in use or OMAP
>>> is in retention.
>> Just to confirm, these 18 days are already on N800 with OS2008 and with
>> those sw issues fixed?
>
> I don't remember if i checked exactly the sw version that is public atm
> but if it wasn't then it was close enough.
>

I can't imagine those fixes are in the current software, or anything close to them as a few weeks ago I performed an idle run-down test on an N800 with 2.2007.50-2 (a freshly flashed device with no configuration changes whatsoever, so essentially a factory fresh install with a fully charged battery). After 12 days and 2 hours[1] the low battery alarm began to sound - that is just 2/3rds of what you are saying is possible so why such a large discrepancy - could my 9 month old N800 battery really have lost 1/3rd of it's capacity? Or can this difference really be down to component variance (the tested N800 is from March 2007)?

1. https://bugs.maemo.org/show_bug.cgi?id=2602#c20

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igor.stoppa at nokia

Feb 14, 2008, 9:47 PM

Post #8 of 11 (1204 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Hi,
On Fri, 2008-02-15 at 02:01 +0000, ext Neil MacLeod wrote:
> Igor Stoppa wrote:
> > On Thu, 2008-02-14 at 14:08 +0100, ext Frantisek Dufka wrote:
> >> Igor Stoppa wrote:
> >>>>> n800: 18 days
> >>>>> n810: 27 days
> >>>> Impressive, any details where the savings were done? Is this strictly HW
> >>>> related and the n800 has same OS2008 version as N810?
> >>> it's both hw and sw; the sw part is about fixing wrong settings in muxing,
> >>> pullup&pulldown and disabling voltage regulators when not in use or OMAP
> >>> is in retention.
> >> Just to confirm, these 18 days are already on N800 with OS2008 and with
> >> those sw issues fixed?
> >
> > I don't remember if i checked exactly the sw version that is public atm
> > but if it wasn't then it was close enough.
> >
>
> I can't imagine those fixes are in the current software, or anything close to them as a few weeks ago I performed an idle run-down test on an N800 with 2.2007.50-2 (a freshly flashed device with no configuration changes whatsoever, so essentially a factory fresh install with a fully charged battery). After 12 days and 2 hours[1] the low battery alarm began to sound - that is just 2/3rds of what you are saying is possible so why such a large discrepancy - could my 9 month old N800 battery really have lost 1/3rd of it's capacity? Or can this difference really be down to component variance (the tested N800 is from March 2007)?

At the risk of sounding like a lawyer, if you check my original post, i
wrote _projected_

That means that over a short run (less than an hour), current is
measured (very accurately) and then applied to the battery capacity.

This test ensures that there are no obvious issues with high to medium
frequency. I am not aware of anybody here really measuring the battery
life over days. I used to do it in 770 times when the activity was a
little bit less hectic (and at that time the test was for only 11 days).

The fixes i mentioned are there, but there might be something else, at a
different level, which compromises the actual achieving of such high
idle times.

We don't use real batteries for he measurement, so that is out of hte
equation in our measurement and i really don't know what's the aging
profile of those batteries.

This is in general why the promised use time is shorter.

When the product is in conception/requirement definition phase, use
times for several use cases are defined and not always in a way that
really stretches the HW/SW capabilities.

So as long as a requirement is met, we are happy with it and move
forward to fix the next bug/issue.

With 770 the focus was on idle time, then with the first releases on
n800 it started moving to idle & connected and n810 has brought more in
the hot spot _active_ use time.

--

Cheers, Igor

---

Igor Stoppa
Next Generation Software
Nokia Devices R&D - Helsinki
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eero.tamminen at nokia

Feb 18, 2008, 2:47 AM

Post #9 of 11 (1199 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Hi,

ext Neil MacLeod wrote:
> Igor Stoppa wrote:
>>>>>> n800: 18 days
>>>>>> n810: 27 days
>>>>> Impressive, any details where the savings were done? Is this strictly HW
>>>>> related and the n800 has same OS2008 version as N810?
>>>> it's both hw and sw; the sw part is about fixing wrong settings in muxing,
>>>> pullup&pulldown and disabling voltage regulators when not in use or OMAP
>>>> is in retention.
>>> Just to confirm, these 18 days are already on N800 with OS2008 and with
>>> those sw issues fixed?
>> I don't remember if i checked exactly the sw version that is public atm
>> but if it wasn't then it was close enough.
>
> I can't imagine those fixes are in the current software, or anything close
> to them as a few weeks ago I performed an idle run-down test on an N800 with
> 2.2007.50-2 (a freshly flashed device with no configuration changes whatsoever,

I.e. you didn't restore a backup, configure a phone nor WLAN?

> so essentially a factory fresh install with a fully charged battery). After 12
> days and 2 hours[1] the low battery alarm began to sound - that is just 2/3rds
> of what you are saying is possible so why such a large discrepancy

Igor, the 18 day number, is that until the device (is calculated to)
shut itself down, or until there's the low battery warning?

> could my 9 month old N800 battery really have lost 1/3rd of it's
> capacity?

And you verified that it really was the original N800 battery and
charger? (I sometimes use the 770 ones, but I think its battery
has smaller capacity)

> Or can this difference really be down to component variance (the tested N800
> is from March 2007)?
>
> 1. https://bugs.maemo.org/show_bug.cgi?id=2602#c20

- Eero
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gmane at nmacleod

Feb 18, 2008, 3:20 AM

Post #10 of 11 (1192 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

Eero Tamminen wrote:
>> I can't imagine those fixes are in the current software, or anything close
>> to them as a few weeks ago I performed an idle run-down test on an N800 with
>> 2.2007.50-2 (a freshly flashed device with no configuration changes whatsoever,
>
> I.e. you didn't restore a backup, configure a phone nor WLAN?
>
I definitely didn't restore a backup or configure phone/WLAN - on the first boot I only configured the language (step 1 I think) and then I quit the wizard before pairing with a phone. I didn't even modify any of the desktop applets - everything was left as it comes in the firmware image, and WLAN was not configured.

> > could my 9 month old N800 battery really have lost 1/3rd of it's
> > capacity?
>
> And you verified that it really was the original N800 battery and
> charger? (I sometimes use the 770 ones, but I think its battery
> has smaller capacity)
>
It's definitely the original N800 battery. As for the charger I've been using the Nokia CA-100 USB charger - should this make a difference?

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igor.stoppa at nokia

Feb 18, 2008, 3:55 AM

Post #11 of 11 (1197 views)
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Re: What is Best practice for Battery Longevity on N8X0? [In reply to]

On Mon, 2008-02-18 at 12:47 +0200, Eero Tamminen wrote:
> Hi,
>
> ext Neil MacLeod wrote:
> > Igor Stoppa wrote:
> >>>>>> n800: 18 days
> >>>>>> n810: 27 days
> >>>>> Impressive, any details where the savings were done? Is this strictly HW
> >>>>> related and the n800 has same OS2008 version as N810?
> >>>> it's both hw and sw; the sw part is about fixing wrong settings in muxing,
> >>>> pullup&pulldown and disabling voltage regulators when not in use or OMAP
> >>>> is in retention.
> >>> Just to confirm, these 18 days are already on N800 with OS2008 and with
> >>> those sw issues fixed?
> >> I don't remember if i checked exactly the sw version that is public atm
> >> but if it wasn't then it was close enough.
> >
> > I can't imagine those fixes are in the current software, or anything close
> > to them as a few weeks ago I performed an idle run-down test on an N800 with
> > 2.2007.50-2 (a freshly flashed device with no configuration changes whatsoever,
>
> I.e. you didn't restore a backup, configure a phone nor WLAN?
>
>
> > so essentially a factory fresh install with a fully charged battery). After 12
> > days and 2 hours[1] the low battery alarm began to sound - that is just 2/3rds
> > of what you are saying is possible so why such a large discrepancy
>
> Igor, the 18 day number, is that until the device (is calculated to)
> shut itself down, or until there's the low battery warning?

heh, first of all i don't see much difference when we talk in terms of
days, considering that the notification itself with bells and whistles
would probably eat up a good deal of idling time.

Then, I intentionally let out all the magic used in battery prediction
and user management (what you see from the battery UI is not always what
you get, but rather what you _should_ think =)

It's a basic calculation done with battery capacity and average idle
current over a relatively short time (tens of minutes).

> > could my 9 month old N800 battery really have lost 1/3rd of it's
> > capacity?
>
> And you verified that it really was the original N800 battery and
> charger? (I sometimes use the 770 ones, but I think its battery
> has smaller capacity)
>
>
> > Or can this difference really be down to component variance (the tested N800
> > is from March 2007)?
> >
> > 1. https://bugs.maemo.org/show_bug.cgi?id=2602#c20
>
> - Eero
--

Cheers, Igor

---

Igor Stoppa
Next Generation Software
Nokia Devices R&D - Helsinki
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