vi /etc/default/grub
Change
GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash”
To
GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash pcie_aspm=force pcie_aspm=force i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1″
update-grub Saves about 10 Watts you battery now should last about 3 to 3.5 hours depending on what you do of course