A method and medium are provided for enabling reliable indication of the amount of time a battery will provide sufficient charge to power a computing device. In one embodiment, the time interval that lapses from the charge draining from the battery between two thresholds is determined, and the thresholds are adjusted based on the time interval. Other embodiments provide for classifying a battery as no longer capable of maintaining sufficient charge by comparing the maximum amount of charge the battery could store to the current maximum amount of charge the battery can currently store. Another embodiment determines how long a battery will provide sufficient charge to power a computing device based on profiles of user activity and associated battery drain rates. The current amount of charge stored in the battery is divided by the profile drain rate to determine how long the battery will provide sufficient charge to power the computing device.