I have a feeling, that every time i hear some musik with my n900, and the screen is not on, the battary is somehow goes down 2x faster then when i am an the web.
today in scool , i was with wife in the internet for about 2 hours with a full charged battary , and the battary droped to 80 percent. or maybe 70 ...

then i was in art lesson and turned on musik, shut down the wife, and then !!! after 2 hours, the battary was at 30-20 percent.

So why , when i just listen to musik with earphones, even not very loud, in 2 houers the battary loose 50 % ??? i mean, wtf is he doing ?

i will install today that battary tool , and record this ...
but maybe someone has the same problems ...

ADDED

I have made some things since yestersday:
i switched from dual to gsm
i removed the weather tool from the desktop
i uninsalled some things ...
I disabled gps

So yes , like in the picture i will add, you can see , with musik it last now longer ...

But what is wonderng me , from 24:00 to 6:00 i turned OFF the WIFI with some extra tool and turned on the OFLINE mode. SO , why !!! he still looses so much energy in 6 hours ??? If i would draw that line , the battary will be empty in 3 days DOING nothing ... i just cant understand it. I turned everything off , the only thing was on is the alarmclock ... so why would a mobile phone, while doing nothing get empty in 3 Days !!!

so here is a screenshot i made in battery eye.



The time is what i realy did , you can see it nor 100 % on this picture
1) The battary was full, WIFI OFF and OFFLINE MODE
2)´Alarm, serving 10 m
3)Musik about 30 m nothing else
4) Tunrned OFFLINE MODE OFF and switched to WIFi in the school , used it in the lesson to goole things
5) turned wife off
6) Musik ...
7) Just turned on wifi , and internet , and musik ,and some windows ...