Working with a notebook, by default, it might be difficult to work with it on the battery more than two hours. It is not very helpful when you can not plug in to AC power nearby.
There are several ways to optimize your notebook’s battery life. All the tips provided have been tested on a HP Pavilion dm4 Notebook PC running Debian Squeeze 6.0.3. In this part, I will show you three utilities : gnome-power-preferences, xbacklight and xrandr.
gnome-power-preferences is part of the GNOME desktop. It helps you configuring basic actions whether your notebook runs on battery or on AC power. Below are screenshots showing my own settings :
xbacklight may be used as well to control backlight brightness using RandR extension.
To get the actual value :
fool@localhost~:$ xbacklight -get
100.000000
to dim this value by 50 percent for instance :
fool@localhost:~$xbacklight -dec 50.00
More information : xbacklight -help
Last but not least, here is the well-known xrandr. With this program, we can collect all the information concerning the video outputs of the notebook. Some graphics card may activate all its video outputs by default. For sure, you do not use of all them in the same time. Desactivating the non-used ones may help your battery feel better 
fool@localhost:~$xrandr -q
Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
VGA1 disconnected (normal left inverted right x axis y axis)
LVDS1 connected 1366×768+0+0 (normal left inverted right x axis y axis) 309mm x 173mm
1366×768 60.1*+ 40.1
1360×768 59.8 60.0
1024×768 60.0
800×600 60.3 56.2
640×480 59.9
LVDS output stands for your LCD panel. Do not desactivate it. If no cable is connected from your VGA output, desactivate it with the following command :
fool@localhost:~$ xrandr –output VGA –off
These are basic tools to make a better use of your notebook’s battery. In the next parts, a few other tools will be presented with a much better tuning capability.
