Battery problems

[AC Question]

my battery is 15% but while i put it in charge it comes to 20%.. and everyday i have to charged my mobile.when i play games suddenly my mobile shuts down while my battery is 35% and shuts again plzz help me..i have samsung S3 mini
Thank

 

[B. Diddy]

Welcome to Android Central! Your battery might be failing. Try a new one.