I had the same problem with my iPhone 4 and it kept doing that and every while it shuts down at 7% than 10% than 15% than 20%! And I had to sold it! I really don't want the samething to happen to my iPhone 5! Because my parents won't buy me another phone? I don't have warranty and I can't change the battery because it's expensive!
Help me please I'm literally crying:(
Read more: Why does my iPhone 5 shuts down at 7%?