Evaluate the efficiency of Windows 7 Power Plan settings

Greg Shultz shows you how to use Windows 7's PowerCfg command line tool to evaluate the efficiency of your Power Plan settings.

A colleague recently asked me if was really true that Windows 7 power-management settings were more efficient and would allow longer battery life when running on a laptop. I told him that based on my experience with running Windows 7 on my laptop it did indeed appear to be true that improvements in Windows 7 power-management technologies provided me with longer battery life.

Of course, in order to get as much battery power as possible out of a single charge, I must admit that I did spend some time tweaking my Power Plan settings in the Control Panel's Power Options tool. I also uncovered a new feature in Windows 7's PowerCfg command-line tool that allowed me to evaluate the efficiency of my Power Plan settings.

In this edition of the Windows Vista and Windows 7 Report, I'll briefly examine Windows 7's Power Plans. I'll then show you how to use Windows 7's PowerCfg command-line tool to evaluate the efficiency of your Power Plan settings.

This blog post is also available in PDF format in a free TechRepublic download.

Windows 7 power-management improvements

Before I get started on the Power Plan settings in the Control Panel's Power Options tool, I want to take a moment to point out that Microsoft has spent a great deal of time analyzing all the different components in the computer and the operating system that are responsible for consuming and managing power use and they have vastly improved power-management capabilities in Windows 7.

In fact, the "Power Management in Windows 7 Overview" white paper on TechNet describes a host of improvements in the operating system that include such things as:

  • In-box device driver support for the latest processor power-management technologies from leading independent hardware vendors.
  • Better management of idle activity by removing or coalescing background activity to ensure that systems can enter low-power states more frequently.
  • New trigger start service capability to allow background processes to start only when a specific event occurs.
  • Adaptive Display Brightness improvements more quickly dim the display after a period of inactivity.
  • New optical drive features that spin discs more efficiently during DVD playback, thus consuming less processing power.
  • Low-battery life notifications are more prominent and more informative.
  • More precise power-management policy feature using a new power WMI provider will allow IT pros to better manage power and troubleshoot related problems.

(You can also download the "Power Management in Windows 7 Overview" white paper in PDF format.)

The Power Plans

When you access Power Options in the Control Panel, you'll see the Power Options page, shown in Figure A. (Keep in mind that there are slight differences on the Power Options page depending on whether Windows 7 is installed on a laptop or a desktop.) There are three power plans to choose from.

Figure A

The Power Options page presents three power plans to choose from.

As you can see, each of the three power plans provides you with a brief description of the energy savings and performance of each plan. The first one is the Balanced power plan, which is selected by default and is designed to offer full performance when you need it and save power during periods of inactivity. The Power Saver power plan will save power by reducing system performance and is designed to help laptop users get the most from a single battery charge.

Hidden by default, and on the other end of the spectrum, is the High Performance power plan, which is designed to maximize system performance and responsiveness but will do almost nothing to save power. As such, from the standpoint of running a laptop on battery power, you might just want to ignore the High Performance power plan.

Customizing power-plan settings

Adjacent to each of the Balanced and Power saver plans, you'll notice a link titled Change Plan Settings. Clicking this link takes you to the Edit Plan Settings page, shown in Figure B.

Figure B

You can alter many of the settings in each of the default power plans.

On this page, there are two categories: On Battery and Plugged In, under which you can alter settings. To conserve the amount of power used by the display on a laptop, you can adjust the amount of idle time that must elapse before the display is dimmed (shifted to a lower power consumption stat) and before the display is turned off. And, while we're talking about the display, you should note that you can also adjust the amount of power that is consumed by the display when it is in use, by adjusting the brightness level setting. Of course, you can adjust the amount of idle time that must elapse before the computer is put into sleep mode.

If you want more granular control, you can click the Change Advanced Power Settings link, which displays a Power Options dialog box with a single tab titled Advanced Settings, as shown in Figure C.

Figure C

The Advanced settings appear in a traditional dialog box interface.

As you can see, in addition to the more common power settings, there are a host of power-consuming features and devices for which you can adjust settings, such as the desktop background, wireless adapters, and USB devices, just to mention a few.

For example, you can regulate how a wireless adapter consumes power by choosing maximum performance or low, medium, or maximum power savings, as shown in Figure D.

Figure D

You can adjust power-consumption settings for a host of power-consuming devices, such as wireless adapters.

Using the PowerCfg utility

To use the PowerCfg utility, you'll need to open an Administrator Command Prompt. At the prompt, type the command

powercfg -energy

After you press [Enter], the PowerCfg utility will begin analyzing your system's power-option settings. After a minute or so, you'll see a report brief and will be prompted to open the report titled energy_report.html for more details. The process is shown in Figure E.

Figure E

When the PowerCfg utility is finished analyzing your system's power-option settings, you'll be prompted to open the report file for more details.

You can type energy-report.html at the prompt to launch Internet Explorer and open the HTML report file.

When the report opens, as shown in Figure F, you'll see a header with basic system information followed by color-coded sections that indicate the severity of the problems that were detected. Pink indicates errors, yellow indicates warnings, and white indicates general information. You can use this report to make adjustments to your power-plan settings.

Figure F

The report is divided into three color-coded sections that provide details on the efficiency of your system's energy usage.

To delve even deeper into the power-management information contained in the report, you should download the "Using PowerCfg to Evaluate System Energy Efficiency" document from the Windows Hardware Developer Center. This document provides you with additional information on how to use the PowerCfg command as well as detailed explanations of how to understand and solve the reported energy-efficiency problems and warnings.

What's your take?

What's your take? Are you using Windows 7 on a laptop? Are you getting more out of a single battery charge than you were with a previous operating system? Have you used the Windows 7's PowerCfg command-line tool to evaluate the efficiency of your Power Plan settings? As always, if you have comments or information to share about this topic, please take a moment to drop by the TechRepublic Community Forums and let us hear from you.

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