Many laptop users rely on the manufacturer supplied software to monitor the laptop battery status and condition while few are the users that perform power efficiency reports which can help them fix power related issues. The Powercfg command in Windows 7 enables users to control the power settings and it has a slew of command options such as, listing all power schemes of the current configuration, displaying the contents of a specified power scheme, changing a setting in the current power scheme and many more. To list all options, type powercfg /? from an elevated command prompt.
Before you optimize your laptop power settings I suggest a power efficiency report is created using the powercfg command line tool. This command will analyze the system for common energy-efficiency and battery life problems while it reports errors and warnings with descriptions. To create the report in html format, from an elevated command prompt type:
powercfg -energy -output [filename.html]
It is recommended to run the powercfg with the energy option when the computer is idle with no open programs or documents.
Another useful output from the energy option of the powercfg command is when testing the battery condition of your laptop. Such a report will contain a battery section including the battery type and charging conditions. If the value of the Last Full Charge is significantly less than the Design Capacity value then the battery is losing its charging capabilities and may indicate degradation! Run the powercfg -energy command from an elevated command prompt and search for the last three lines within the battery section. The battery section may show under the errors section when its state is considered degraded as shown below:
The powercfg command has more options such as, the hibernate option which was introduced in Windows Vista. The Hibernation mode can be turned on or off using the command-line by typing:
powercfg /hibernate [on|off]
Windows 7 has a new power option (since Windows Vista) that is a blend of low power consumption as in Sleep mode and saving the state to the hard drive as in Hibernation mode. It is a combination between Sleep and Hibernation modes which gives users the ability to go into low power mode while saving any opened applications and documents. This new mode can be set from the Power Options dialog box found in the Change advanced power settings in Control Panel\All Control Panel Items\Power Options\Edit Plan Settings.