Okay, so Iv'e had my s3 for about 3 months now, its built in with Android 4.3. and is working fine. The only problem is dreadful battery drainage. yeah it used to work fine and last longer but now it's not that good. My dad bought me an additional battery from MPJ as backup. It is much better with two batteries but idk why it drains batteries very fast. I need to know why and I'm really trying to be careful about my usage. Is it possible because of the system update?? Is there anyone out there who knows a simple way to fix this problem? if so please and thank you.