when u boot up a N900 it consumes a certain amount of power because like a computer it takes a lot of power to start up then it goes idle once u don't use it and it either shows the battery going back up or just doesn't move but it depends on how many stuff u use in the background mines is stock no mods and my battery lasts me around 15 hours with minimum wifi and gprs use and doing other lil things. experimenting with the battery for 3days now to see the best way to use the phone for me at least