The iPhone normally tells you when the battery is low. It will give you a warning when the battery level reaches 20 percent. How about if you let it keep running down? Website College Humor has some answers.
We’ve probably all received that low battery warning at some point. Sadly, they are never as much fun as these. That said, a lot of these have some bit of truth to them. Nobody wants to be without their iPhone in an emergency.
Have a look at the rest of the low battery warnings here.