I have a 2.6GHz Haswell i5, 8GB RAM, 256 SSD 13" from late 2013. My battery life has become pretty bad, far less than 9 hours. The only things I've done is: 1. changed my resolution to 1680 x 1050 2. turned on FileVault 2. 3. Brightness half 4. keyboard back light mostly off but sometimes half lit 5. bluetooth on. If I watch videos on YouTube, THE BATTERY LIFE IS IS PITIFUL!