Hi, i just bought my S advance about a week ago. I realised that my phone's battery can't last for more than a day. I have task killer and i killed those apps whenever i want to lock my screen. I tried to off my wifi, but about 12hours, my battery had gone down to 20-30%. I only use it to call a few ppl and play a little games (less than 15mins). Anyone experiencing this battery issue?