Remaining battery indication

Ran the battery all the way out yesterday, only to discover that the notification that Chrome pops up isn't accurate.  It counted down from 15 minutes to 7 minutes - and then shut down with no further warnings.  Did get some awesome battery life up until then, though.  The Cr-48 was off the charger for 12 hours and in pretty steady use by both my daughter and myself.  The active usage was easily 8+ hours.