[ronan manuel]

So my dad gave me his phone when he gets to go home from abroad. It is a Samsung Galaxy S3 Kernel version.. My dad already complained about the annoying battery life of the phone. He rarely uses it just for texting and he doesn't even play games. It usually stuck at a certain percent when I charge it. I tried restarting it and it rarely changes. It notoriously gets static like effect from the screen when below 40% then depletes instantly from 5% then drains to zero. Can someone know the problem? The battery was replaced by a new one by my dad but it seemed it was not the main cause.