it depends on the screen brightness etcbut i found when i was using it alot of the time with the screen brightness at medium it lasted about 12 hours
but i was using it all day on the day i can remember so it will be more if you change the screen brightness and keep the screen off most of the time here the openmoko's page about the battery http://wiki.openmoko.org/wiki/Neo_FreeRunner_Battery#Notes_about_expected_battery_life
