[maemo-users] What is Best practice for Battery Longevity on N8X0?

From: Igor Stoppa igor.stoppa at nokia.com
Date: Thu Feb 14 11:50:19 EET 2008
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.

> > 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

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


Cheers, Igor


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

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