Haha, a magnet caused the battery drain.. who would have thought it? Thanks for posting, this is good to add to the repository of possible solutions/causes for the next person with battery charge problems.

It has been said before, in bugzilla by one of the developers, that there is absolutely no reason to use 10mW setting instead of 100mW setting for WiFi. It is apparently only there for support of legacy WiFi standards (think original b time period), and does not provide power savings, despite what it might lead you to believe.

I wish I had the bug ticket number to link you to, but just a heads up.

Sounds like https://bugs.maemo.org/show_bug.cgi?id=2821#c6

I am glad this thread was started because this is something to be aware of for many of us. However, I believe there are still other power eating bugs to be resolved.

I wish I was able to provide more detail, but frequently I go to bed with more than 1/2 charge and wake up to a fully discharged phone. I am absolutely sure that there were no apps running when I placed it on my table. I am absolutely sure that the last thing I did was disconnect from my wifi router after closing MicroB. I am not yet sure what to attribute it to. But I know it was not due to any magnets since there are no magnets near that night table.

and i have this:
http://talk.maemo.org/showpost.php?p=1838&postcount=10

it's quite old but the way a wifi chip works hasn't changed. ^^

OK, I have a suspect: omap2_mcspi

I noticed that after disconnecting from my Belkin wireless router load-applet reported quite a bit of activity, never really going beneath 8 or 9%. I fired up top and noticed that omap2_mcspi was consistently staying at the top of the processes. I noticed this same thing the other night and I woke up to a drained device. Not wanting to go through the same thing, I rebooted. After allowing a few minutes for the indexing processes to reach their idle state, load-applet is reporting 2 or 3% activity and omap2_mcspi is nowhere to be found in top. Coincidence or a bug?

I totally agree with you - my finding are not absolute and in a device as complex as the N900 there is a magnitude of places battery drain can occur.

My reason for starting this thread is that most of us look towards traditional areas when looking for a solution (is wifi on, how much more power does 3g use etc). My particular source of battery drain was not something I would ever have even thought to look at (and that coming from an electronic engineer with 12 years experience). So if this thread can help just a few people that have been baffled with low battery endurance it was worth typing.

On my side I am still in a much better place with my phone - by the end of the day I still have more than 50% battery life which is about a 4 times imporvement.

Just tried it again. This time I didn't even ran a browser. Just connected to the network and disconnected a minute latter. omap2_mcspi is once again consistently at the top of the processes. I guess I'll have to file a bug. (Now, where in the world is my bugzilla password?)

If any of you have the same problem you can find the bug report here:

https://bugs.maemo.org/show_bug.cgi?id=8848

Is there a publicly writable wiki on maeomo.org somewhere so that we can collect all these findings in some more systematic form? My battery is fine now too, but without scouring the forums, I wouldn't have gotten there.

Now, I use GSM/3G switcher to easily switch on 3G only when I actively surf, leave the Wifi on always and have about 50% battery left when I go to sleep.