Although major desktops like Gnome/KDE or XFCE have power managing utilities (GUI) of their own yet other than setting your Laptop into sleep mode or change brightness, etc there are certain things that an OS can do to help you to enhance your battery life which most of those above mentioned apps fail to achieve.
For instance, there are applications that monitors your entire hardware attached to the Laptop/Netbook, etc thus automatically adjust CPU/HDD or Network cards speeds which result in a longer battery life. If you use Fedora Core (15 or below) then there is an application called "tuned" which does exactly that!.
tuned basically has three main "parts".
|Tune it using "tuned" :)...|
1. CPU - This portion of the application monitors your CPU and depending on your CPU load it "adjusts" your CPU and lower its power usage, etc.
2. HDD - This monitors the hard disk drive and depending on the HDD usage "tuned" will slow them down (spin down) since HDD is one of the main power consuming hardware attached to your Laptop.
3. Net - This will tune the Network cards depending their "load".
So if you use Fedora Core 15 or below, you can install tuned easily by opening a Terminal and entering the below command.
yum install tunedThen after the installation is complete, run it using the below command (which will also add it to the "system services").
service tuned startIf you want to make it to run automatically every time your OS boots then, use the below command afterwards.
chkconfig tuned onDon't expect this app to do "wonders" for your Laptop's battery life, yet it is pretty handy nonetheless. Oh btw, as said, you don't have to do anything, just install and run it... it'll do the rest for you :). Enjoy!.