Why is my battery draining so quickly?

[AC Question]

Battery problem

I have a Galaxy S4 and the battery started dropping very quickly from 100% to 75% and then it turns off completely at 30%, I noticed that the battery was bulging so I replaced it, But that didn't fix any of the problems, Can someone tell me a good fix? Thanks in advance

 

[Teejai80]

Hi and welcome to Android Central.

Have you checked your battery usage graph? An application is probably running in the background and draining it.