I recently got a razr HD and i noticed my battery barely lasts a day. I had a flip phone before and it would last a week on one charge, i know i wont get the same type of battery life. I downloaded juice defender and set it to turn off my wifi/data when not in use. It has helped a bit since before that my phone would lose 2% battery an hour just in standby. I haven't downloaded any task killers, but when i'm done with my apps i go in to the settings and close them.