Why is my phone suddenly dying?

Episode 1100 (1:52:57)

Wesley from Alexandria, LA

Wesley has a friend who's phone is fairly new, and it drops to 30% really quickly and shuts down. Leo says that's not right. If it's still under warranty, he should take it back. That isn't the sign of a bad battery. Batteries either work or don't work. What uses the battery most is a screen. So an app really wouldn't kill it so suddenly.