With couple of days old battery it didnt even consume 1 bar when it was most of the day on standby. First bar was consumed after 2nd day (i had used the 770 for like 2-3 hours for offline-html-document reading + calender/to-do-list.)

For those who dont have the device yet, it has 3 bars of battery.

edit: it was offline in the night because i thought it would use the battery without any reason (shutting down takes few seconds and starting it in the morning maybe like 30-60 seconds).