A couple weeks back, I posted a short article on battery life with Windows 8.1 looking at whether or not it had changed compared to Windows 8. The short summary is that no, it did not change appreciably, though at least one of the tests I ran showed worse battery life with Windows 8.1 compared to Windows 8. There are quite a few variables, and we try to minimize the impact of other elements on battery life, but since I cant easily go back and retest the original Windows 8 results its difficult to say for certain if the drop is consistent among laptops or something specific to the Sony VAIO Pro 13.