These quick changes increased my battery life from 5-6 hours to well over 10 hours with a Thinkpad X250. I would highly recommend these for any mobile Ubuntu install.
sudo add-apt-repository ppa:linrunner/tlp sudo apt-get update sudo apt-get install tlp tlp-rdw (For thinkpads continue with) sudo apt-get install tp-smapi-dkms acpitool
Now update your TLP file with
gksudo gedit /etc/default/tlp
Finally Add Powertop
sudo apt-get install powertop sudo powertop --auto-tune sudo powertop
Reboot
