Connected standby SleepStudy
Starting with Windows 8.1, a software tool, SleepStudy, is available as an inbox component in all Windows PCs that implement the connected standby power model. SleepStudy can measure connected standby performance with minimal impact.
Watch this video to learn how to use SleepStudy to find and fix components that cause unexpected battery drain.
Tracking system activity and battery drain during connected standby can be difficult because the tracking itself can cause unnecessary activity and battery drain. For example, traditional disk-based logging has the unwanted side effect of causing excessive battery usage when the disk is activated for logging. In contrast, the SleepStudy tool is designed to avoid generating activity that could interfere with the connected standby performance that it measures.
The most detailed way to measure power consumption during connected standby is to use an instrumented system, which is a physical system that has power measurement leads connected to every major hardware subsystem of interest. However, testing to this level of detail is not practical in many cases because of engineering cost, and systems that have already been sold to customers typically cannot be tested in this way.
The SleepStudy tool provides overview information about each connected standby session. This information includes the active time, the idle time, and the power consumed. A session starts when the system enters the connected standby state, and ends when it exits this state.
SleepStudy also provides first-level information about the causes of activities that occur during each connected standby session. This feature allows for easy investigation of long-running activities.
The SleepStudy tool runs from a Command Prompt window and is simple to use. SleepStudy outputs an easy-to-read HTML report.
To run SleepStudy, open a Command Prompt window as Administrator and enter the following command:
In response to this command, the built-in powercfg.exe command-line tool creates an HTML file named Sleepstudy-report.html in the current working directory.
The following screenshot shows how to run SleepStudy.
By default, the SleepStudy report covers the last three days of system operation. To change the duration covered by the SleepStudy report, use the powercfg.exe tool's
/duration option. With this option, you specify an additional parameter, which is the number of days (up to 28) that the SleepStudy report covers.
For example, to generate a SleepStudy report for the last seven days of system operation, open a Command Prompt window as Administrator and enter the following command:
powercfg.exe SleepStudy /duration 7
For more information about powercfg.exe, see Powercfg Command-Line Options.
The SleepStudy report is organized as a series of connected standby sessions. A connected standby session is defined as one instance of the screen turning off and then back on again.
You can use the SleepStudy report to observe and diagnose common connected standby problems. The examples in this article show how to use the report to investigate problems such as high email or network activity, high battery drain, and inability to enter DRIPS.
Each SleepStudy report concludes with information about the system battery configuration.