[maemo-users] Accuracy of the power meter?

From: Igor Stoppa igor.stoppa at nokia.com
Date: Tue May 8 08:51:29 EEST 2007
On Mon, 2007-05-07 at 23:25 -0400, ext Mike Lococo wrote:
> > I've been noticing that I don't get anywhere near the promised "10 days
> > idle" battery life on my N800.  With bluetooth and the wireless turned
> > off (offline mode), and with the display off and keys/touchscreen
> > locked, I'm getting at best 8-10 hours of idle time before the battery
> > is completely drained.  
> That's definitely weird.  I don't get 10 days between charges, but then 
> my N800 is never idle for 10 days at a time.  I commonly run 3 days 
> between charges, though, and I'm a fairly active user.

Yes, apparently it's somehow problematic to convey the difference between
"idle" and "almost idle".

To give a rough idea, the power used by the device while being running
can be _at_least_ 10 times higher, with peaks in the order of a couple
of hundred times.

So it's very hard if possible at all to define what is your expected
runtime apart from few selected use cases that are using for marketing
the device and that we refer to when measuring the power performance.

Of course our use-cases are tailored to cover most of the common uses,
but it's easy for a power user to come up with some combinatioin of
software/use that doesn't allow for proper power saving.

> > I have two theories why at this point.  The first is that the battery
> > has gone south, even though it I've only had the N800 for about a month
> > or os.

I have seen it happening somehow only to 3 years old batteries from the
early 770 era. But that's only my personal experience.

> The second is that I'm running off a 2gig flash card as my root
> > filesystem instead of the internal flash, per the instructions given in
> > the Maemo wiki.
> I don't do this.  If you don't get a more helpful response, I would run 
> with a stock fs and no applications installed for a day (no fun, but an 
> important troubleshooting step if you're not sure where the problem 
> lies). 

MMC / SD shouldn't be an issue. Actually the throughput could/should be
higher because jffs2 does dynamic compression/decompression while the SD
doesn't. Of course there could be a bug in the driver, but history has
usually shown that it's some application/service/daemon that is run too
often or that does busy loop or similar nasty things.

> If you still have low standby life in offline/screenlocked mode 
> then you definitely have hardware issues.  If not, then you can start 
> introducing variables in a controlled way until you pin down the rogue 
> config/app that's killing your battery life.  Please report back so 
> others can learn as well.

Yes, that's the only certain way. My advice is to start removing first
those apps that are likely to introduce periodic activity.
Cheers, Igor

Igor Stoppa <igor.stoppa at nokia.com>
(Nokia Multimedia - CP - OSSO / Helsinki, Finland)

More information about the maemo-users mailing list