I have noticed that my battery icon it stays full green almost all the time, yesterday I used my phone a lot and the battery was more than 3/4 green, I started to use safari and in less than 5 min the phone turned off, when I tried to turned on the EMPTY battery icon came on. it had no charge.
I didn't even got the 20% of battery left alert.
I didn't even got the 20% of battery left alert.