When my daughter came home, she plugged her phone in to recharge it to 100%. After about 3-1/2 hours, it was down to 30%. Her screen usage was at 49%, she has it set to auto brightness and Android system battery usage was around 30%. She was connected to WiFi, and I have no idea what is killing her battery so fast. I know inside the house, our phones will constantly switch between 3G and 4G. But by comparison, my Note II screen usage is at 10%.
Maybe turn off Mobile Data while connected to wifi?