This is the second time this has happened to me: I had a full nights charge and barely used my phone at all today. I was just watching a hockey game and at the end of the period, I noticed my phone LED was blinking red and the battery warning came up that said it had 5% battery left. The battery indicator in the notification bar was red. First, I plugged my phone into the charger just to see what would happen. Nothing, it still told me my battery was at 5%. Previously when I had this problem, I rebooted my phone and the battery meter showed the correct value. So, I rebooted my phone, and when the screen came back on, I had 60% battery remaining and the battery meter was green.