The specification states that the icon should turn bed based on time (<30 minutes) and not on percentage:
https://wiki.ubuntu.com/BatteryStatusMenu#Icons
if percentage is being used, then it could be down to bug #629258 ("Battery life estimation never comes around"). You can tell if this is the case by clicking on the battery icon and seeing if it states "estimating".
The specification states that the icon should turn bed based on time (<30 minutes) and not on percentage:
https:/ /wiki.ubuntu. com/BatteryStat usMenu# Icons
if percentage is being used, then it could be down to bug #629258 ("Battery life estimation never comes around"). You can tell if this is the case by clicking on the battery icon and seeing if it states "estimating".