Understanding Battery Life and Power Plans
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.
Windows®-based laptops must meet energy-efficiency regulatory requirements, such as the United States Environmental Protection Agency (EPA) Energy Star program. Furthermore, surveys have shown that longer battery life continues to be a leading request from consumers as a feature of laptops.
Software and hardware factors, if not checked, can cause a significant reduction in battery life, such as a low-capacity battery, a processor-intensive driver, or a poorly-configured power setting. When designing your system, you should experiment with multiple configurations of each of these factors to find the best balance of battery life and performance.
Hardware
Battery capacity. Check with your battery manufacturer to determine the battery capacity.
Other hardware components. Ask your hardware component manufacturers for their power-consumption test results for each hardware component.
For information on each of these battery-life factors, see Mobile Battery Life Solutions: A Guide for Mobile Platform Professionals.
Software
Drivers. Validate each new driver for battery impact. As each new driver is added to the system, observe its impact on power consumption. A single poorly performing driver can greatly affect system performance.
Applications, services, and other software. Validate each new application and system service for battery impact. As each new software application is added to the system, observe the impact to power consumption on the system. A single poorly-performing application can greatly affect system performance.
Windows power policy settings. Optimize Windows power policy settings to balance performance needs and battery life. To set up default power policy settings for your end users, see Configure Power Plans.
For information on each of these battery life factors, see Mobile Battery Life Solutions: A Guide for Mobile Platform Professionals.
Testing
Compare the overall system power to the power consumed using a clean installation. With preinstalled applications and power policies, some computers have shown a 40-percent decrease in battery performance compared with a clean Windows installation. By careful engineering, it is possible to achieve equal or improved performance over running a clean Windows installation.
Determine the causes of heavy battery use by looking at how resources are used. Many system problems can be found by looking at processor idle time. Use a system tool, such as XPerf, to show when the system has spikes in power usage. Performance tools like XPerf can help you target the applications that are causing increased processor use.
For information on how to run battery life tests and to use XPerf, see Mobile Battery Life Solutions: A Guide for Mobile Platform Professionals. For information on XPerf, see Windows Performance Toolkit.