Laptop users are concerned with getting the most out of their battery power. KDE provides a Power Management utility that makes it easy to see your current battery settings and to create power profiles that best match your needs. If you click on the battery icon in your system tray, the Power Management window will open, as seen in Figure 7.4a:
Figure 7.4a: Power Management Window of Battery Widget in the System Tray
If you do not see a battery icon, you may need to click the arrow in the system tray to view hidden icons. If the icon is still not there, you can add this widget to the system tray by clicking on the Panel tool box icon (located in far right corner of the panel) -> +Add Widgets. Search for the term "battery" and double-click the battery icon. You can then click the red X to close the Add Widget window.
As seen in Figure 7.4a, this window will indicate if the battery is plugged in and the percentage of the charge. If you click the Power Profile drop down menu, you will have the option to choose from five power profiles: Performance, Powersave, Agressive Powersave, Xtreme Powersave, and Presentation. The rest of this section will show you how to view and modify the settings for each power profile.
If you wish to conserve some battery power, you can use the slider to adjust the screen brightness to the lowest usable level.
If your BIOS supports it, you can click the Sleep or Hibernate buttons whenever you wish to enter that mode.
Note: if you encounter problems with Sleep or Hibernate mode, the section on ACPI may help you to diagnose or fix the problem.
If you click the wrench icon, you will enter the Power Management utility, seen in Figure 7.4b. You can also start this utility from Application Launcher -> System Settings -> Power Management.
Figure 7.4b: General Settings Window of KDE's Power Management Utility
The Settings and Profile tab of the General Settings window allows you to configure the following:
Lock screen on resume: if this box is checked, the screen will be locked when leaving suspend mode. This means that you will need to input your password to unlock the screen.
Let PowerDevil manage screen powersaving: if checked, KDE will use DPMS to shut off power to the display.
Before doing a suspend action, wait: the number of seconds KDE will wait before suspending the system (e.g. after closing the lid).
The Profile Assignment section allows you to determine which of the 5 power profiles is used for each of the following situations:
- When AC Adaptor is plugged in
- When on battery power
- When battery is at low level
- When battery is at warning level
If you click the Configure Notifications button, you'll see a screen similar to Figure 7.4c:
Figure 7.4c: Configuring Notifications for Power Management
The upper frame of this window lists various power management events and the lower frame of this window configures the type of notification associated with each event. If you highlight an event, such as "AC adaptor plugged in", you can view and edit the possible notifications:
Play a sound: if checked, the specified sound will play whenever the highlighted event occurs. You can click the white play button to the left of the sound's name to preview the sound. If you would like to change the sound, click the blue browse button to browse through KDE's sounds. If you have your own collection of sounds, you can browse to their location.
Show a message in a popup: if checked, a pop-up message will occur above the system tray whenever the event occurs.
Log to a file: if you would like to save the notification to a file, check this box and click the blue browse button to browse to the location of an existing file (create an empty file first if it does not already exist). Whenever the event happens an entry (for example: - KNotify Tue Nov 23 12:37:23 2010: The power adaptor has been plugged in.) will be added to the bottom of the specified file.
Mark taskbar entry: