Configure Power Plans

  • [アーティクル]

Applies To: Windows 7, Windows Server 2008 R2

Note

This content applies to Windows 7. For Windows 8 content, see Windows Deployment with the Windows ADK.

A power plan is a collection of hardware and system settings that manages how computers use and conserve power. You can create custom power plans to help users configure a power plan that is optimized for their computers.

By default, Windows® 7 and Windows Server® 2008 R2 include three power plans: Balanced, Power saver, and High Performance. You can customize these plans for your systems, or create new plans that are based on the existing plans.

To create a power plan that works best for a particular system design, experiment with different settings, and then test the resulting performance.

Note

  • Optimizing Windows power plans can contribute to improved battery life. However, a single poorly-performing application, device, or system feature can significantly reduce battery life. For information about factors that influence battery life, see Understanding Battery Life and Power Plans.

  • Microsoft® uses the terms power plan and power scheme interchangeably.

    To use custom power plans, you can either customize an existing power plan, or create a new power plan from scratch.

    • In This Topic

    Common configurable settings that can have an impact on battery life

    To set a built-in configuration plan as default

    To create a customized power plan

    To modify a power plan by using the powercfg command

    To capture power plans

    To deploy power plans

    To confirm that the power plan has deployed

    Common configurable settings that can have an impact on battery life

    This section lists a few of the common configurable settings that can have an impact on battery life. Test these and other settings to create an optimal power plan for your system.

    Settings can be specific to whether the computer is plugged in (AC) or on battery power (DC). You can configure the following settings:

    • Display brightness

      The most effective way to reduce the power consumption in a mobile computer when the display is in use is to reduce the display brightness. On a portable computer, the attached display is the largest power consumer, requiring up to 40 percent of the overall system power-consumption budget.

      By default, Windows significantly reduces the display brightness when a mobile computer is on battery power. Depending on your hardware and the needs of your users, you can adjust the default display brightness setting lower to increase battery life, or higher to make the display easier to read.

    • Display dimming

      By default, portable computers running Windows® 7 and Windows Server® 2008 R2 are configured to dim the display after a period of inactivity. This precedes the Display timeout, which turns off the display completely. This can save considerable power on a portable computer that is being used intermittently.

    • Display timeout

      Portable computer battery life can be significantly extended by using a short display idle timeout.

    • Hard disk timeout

      Although the hard disk drive (HDD) is not the primary power consumer in the typical mobile power PC, you may be able to realize power savings by increasing the hard disk timeout.

      When the hard drive is idle for a period of time, the hard drive's motor will stop. The next time the computer needs to access the hard drive, the system response may be slow while the hard drive begins spinning again.

      Depending on your hardware and the needs of your users, you can adjust the default hard disk timeout lower to increase battery life, or higher to increase the availability of the hard disk.

    • Sleep mode

      By default, if the processor is idle, and the end-user is not using the computer, Windows will go into low-power sleep or hibernate modes. The next time the computer needs processor power, system response may be slow while the processor recovers.

      Depending on your hardware and the needs of your users, you can adjust the default sleep timer lower to increase battery life, or higher to increase the availability of the processor.

    • Wireless Adapter power-save modes

      By default, Windows configures the 802.11 power-save mode to Maximum Performance for both AC and battery power.

      This configuration keeps the wireless adapter active, even when data is not being transferred. This alleviates compatibility problems between some wireless adapters and those access points that are not compatible with 802.11 power-save modes.

      If you are creating custom power policies to realize additional power savings and help extend battery life, consult with the manufacturer of the wireless adapter about the effects of changing the power policy value to Maximum Power Saving or Medium Power Saving.

    You can manually modify the power settings for each built-in power configuration. To learn more about these settings and other common configurable power settings, see Mobile Battery Life Solutions: A Guide for Mobile Platform Professionals.

    To set a built-in configuration plan as default

    To set this plan as default, set the Unattend setting: Microsoft-Windows-powercpl\PreferredPlan.

    This power plan appears in the list of featured power plans when the user clicks the battery meter. The default featured power plans are Balanced and Power Saver.

    Add the Windows Unattend setting: Microsoft-Windows-powercfg\PreferredPlan. For information on this setting, see Windows® Unattended Setup Reference.

    To create a customized power plan

    You can create a customized power plan, and modify most of the configurable power plan options through the Windows Control Panel. You can modify the other configurations by using the powercfg command, described later in this topic.

    1. Click Start, and select Control Panel.

    2. Click Hardware and Sound, and select Power Options.

      The Power Options control panel opens, and the power schemes appear.

    3. Click Create a power plan.

    4. Follow the on-screen instructions to create and customize a power plan based on an existing plan.

    To modify a power plan by using the powercfg command

    You can customize all configurable Windows power options, including hardware-specific configurations that are not configurable through the Windows Control Panel, by using the powercfg command from an elevated command prompt.

    Open an elevated command prompt

    1. On your technician computer, click Start, click All Programs, and click Accessories.

    2. Right-click Command Prompt, and select Run as administrator. If prompted for permission, click Continue.

      The Command Prompt window opens, with the title "Administrator: Command Prompt".

    List the available power plans

    On your technician computer, at an elevated command prompt, type

    powercfg -LIST

    The computer will return the list of available power schemes. The following examples refer to this as guidScheme1 and guidScheme2.

    Existing Power Schemes (* Active)
-----------------------------------
Power Scheme GUID: {guidScheme1}  (Balanced) *
Power Scheme GUID: {guidScheme2}  (Power saver)

    Note the GUIDs listed next to the power schemes you want to change. You will need these GUIDs later, when manually updating settings and capturing the power plans.

    Set the power plan to be modified as active

    To modify a plan, set the power scheme you want to change as the active power scheme. For example,

    1. powercfg -SETACTIVE {guidScheme2}

    Locate and adjust the settings

    This section describes how to manually configure other power configuration settings by using the powercfg command. Test these settings to create an optimal power plan for your system.

    1. To adjust other power plans settings, at an elevated command prompt, type:

      powercfg -QUERY

      If the QUERY command is successful, then the computer will display information for the power settings for this scheme.

    2. Review the information from the query command, and note the Subgroup GUID for the specific setting you want to change. For example, to review the settings related to Display, type:

      Subgroup GUID: {guidSubgroup-Display}  (Display)

    3. Review the information from the query command, and note the Power Setting GUID for the specific setting you want to change. For example,

      Power Setting GUID: {guidPowerSetting-Brightness}  (Display brightness)

    4. Review the information from the query command, review the possible settings, and find a value that works for your computer.

    Note

    You enter these values using decimal integers, but they are displayed as hexadecimal values specific to the setting. 

    For example: You enter values for display settings as a percentage. When you enter a level of 50% brightness as 50, it is displayed as 0x00000032.  
  

    Power Setting GUID: {guidPowerSetting-Brightness}  (Display brightness)
          Minimum Possible Setting: 0x00000000
          Maximum Possible Setting: 0x00000064
          Possible Settings increment: 0x00000001
          Possible Settings units: %
        Current AC Power Setting Index: 0x00000064
        Current DC Power Setting Index: 0x00000032

    1. Adjust the value for the power setting for times when the computer is plugged in. For example, to set the brightness level to 100% when the computer is plugged in, type:

      powercfg -SETACVALUEINDEX {guidScheme-New} {guidSubgroup-Display}  {guidPowerSetting-Brightness} 100

    2. Adjust the value for the power setting for times when the computer is on battery power. For example, to set the brightness level to 75% when on battery power, type:

      powercfg -SETDCVALUEINDEX {guidScheme-New} {guidSubgroup-Display}  {guidPowerSetting-Brightness} 75

    3. Verify the setting. Type:

      powercfg -QUERY

      The computer will show the new power setting index in hexadecimal notation. For example,

      Power Setting GUID: {guidPowerSetting-Brightness}  (Display brightness)
      Minimum Possible Setting: 0x00000000
      Maximum Possible Setting: 0x00000064
      Possible Settings increment: 0x00000001
      Possible Settings units: %
    Current AC Power Setting Index: 0x00000064
    Current DC Power Setting Index: 0x0000004b

      This example shows the hexadecimal value 0x00000064, representing 100% display brightness while plugged in, and the hexadecimal value, 0x0000004b, representing 75% display brightness while on battery power.

    To capture power plans

    After you have created power plans that work for your system, capture the power plans from your technician computer, and deploy them to your destination computers. For example, to export a power plan from your technician computer called OutdoorScheme, open an elevated command prompt and then type:

    powercfg -EXPORT C:\OutdoorScheme.pow {guidScheme-New}

    To copy this file to your reference or destination computers, add this file to your distribution share, as described in Understanding Distribution Shares and Configuration Sets.

    To deploy power plans

    The following steps can either be typed on the reference or destination computer, or can be automated by using custom scripts. For information about creating scripts, see Add a Custom Script to Windows Setup.

    1. Import the power plans. For example, to import a power plan called OutdoorScheme, at a command prompt, type:

      powercfg -IMPORT C:\OutdoorScheme.pow

    2. Set a power scheme to be the active power plan. For example,

      powercfg -SETACTIVE {guidScheme-New}

    To confirm that the power plan has deployed

    Confirm that the power schemes are present on the system. To do this:

    1. Click Start, and select Control Panel.

    2. Click Hardware and Sound, and select Power Options.

      The Power Options control panel opens, and the power schemes appear.

    3. Review each power scheme.

      The power scheme set as active will be used as the active power scheme.

    See Also

    Concepts

    Configure Other Windows Options