When I got my first laptop I went strait for my ubuntu disk and never installed windows on the machine. I didn’t realize how bad my battery life was until my office supplied me with a inspiron D830 (same motherboard, basically the same hardware). The windows machine for my office had about 4.5 hours of battery life, while my Linux machine was topping out around 3.5 hours.
There are some things you can do with your Linux laptop to increase the life of the battery. I will keep editing this post over time as I come across new ways to reduce power consumption.