Battery life Dell XPS 13 Developer

Hi,

I have received my new Dell XPS Developer  and almost everything is working fine: backlit keys and  'window' key are working,   as well as touchpad gestures, sound, camera, ... .

The bios  installed by Dell is  A07.

I have upgraded to  Ubuntu 12.10 and installed gnome-shell  without problems. So, I am very happy with it.

I have only one issue. Once the battery is 100% charged, I see that  it gives me  only 3 hours of battery life.

I have installed laptop-mode-tools (https://wiki.ubuntu.com/PowerManagement) but I do not see any improvement. Any idea to solve  this?

BTW, congrats to Dell / Canonical  team for this awesome linux experience :).

Thanks, 

           Carlos A.