I have a 2013 13" Macbook Air and I've noticed a drastic drop in battery life the past few months. I used to get about 7-8 hours and now it's about 4. I'm not sure if it's because I mostly use Windows 7 via Bootcamp on it. Have other people had this issue? I guess I'll need to try running Yosemite all day and see if I notice the same problem. But for school and work, I need Windows.