After updating to PR1.1 I noticed a drastic increase in battery drain. Long story short, I figured out it was Firefox that caused it and uninstalled it. The battery was fine the whole day, didn't drain almost at all, since I didn't do much with the phone.

I went to bed, battery fully charged, device idle, no wireless connections.

The next day it had turned itself off. I tried to turn it on, but it said that the battery was low and turned itself off again. Suspicious, I connected it to the charger and let it charge for a few hours until the indicator light turned green.

The rest of the day went without problems. As I didn't do much with it, the battery stayed full, only showing a small decrease towards the end of the day. I went to bed, battery (almost) full, device idle, no wireless connections.

You can imagine my surprise the next day when the N900 was turned off AGAIN. Battery empty.

Tl;dr: The battery doesn't drain during the day, but during the night it magically purges all of its contents.

Running the top command, or Conky, doesn't show anything weird.

Any ideas what's going on?