I've noticed some battery problems:
- It last less, 1 week instead of 4

- If battery is at 10-5% level the touch screen behavior become "strange", sometimes he doesn't do nothing, sometimes he move 10 pages forwards other times simply wind moves pages... as a real book would do
The same behavior is seen in AllReader and FBReader so it should an OS problem...
So there's some daemon that sucks battery and that should be stopped? I don't pretend the same uptime of Kobo's firmware but at least little more...
There is an App that gives a clear alert when battery is low? The bar on the upper right one could forgot to see... and in any case the device simply could not die suddenly without warnings...