Windows 8.1 devices, as long as they’ve the right hardware, can be put into a network-connected standby state called InstantGo (known as Connected Standby in Windows 8 and Windows RT) , allowing for apps and tiles to retain Internet connectivity and remain updated even when the system is in standby mode. It’s undoubtedly a great feature, but it’s easy to see how a few battery-hogging apps and system activities could combine to ruin its usefulness. Enter Windows 8.1 Sleep Study, a diagnostic tool for analyzing battery usage during InstanGo sessions.
A few days back, Microsoft detailed this feature in a post on the
Windows Experience blog
. Available only on Windows 8.1 and Windows RT 8.1 systems with InstantGo support — to check, enter “powercfg/a” into a CMD window and look for “Standby (Connected)” — Sleep Study can be invoked from an elevated command prompt by entering “powercfg sleepstudy.” The report itself is an HTML file that can be found inside the current directory. It includes battery drainage info of all connected standby sessions lasting more than 10 minutes over a 3-day period.
“Sleep Study tells you how well the system slept and how much activity it experienced during that time. While in the sleep state, the system is still doing some work, albeit at a lower frequency,” the company said in a blog post Thursday. “Because the resulting battery drain is not easily perceptible (you can’t see it draining), we built the Sleep Study tool in Windows 8.1 to allow you to track what is happening. We thought of simply using traditional logging to do this, but ironically, the logging itself would drain the battery. With this in mind, we designed the Sleep Study tool to minimize its own impact on battery life, while tracking the battery draining activities.”
“You can use Sleep Study to see which apps and devices are most active during a sleep session. Sleep Study reviews all the sleep sessions longer than 10 minutes and provides you with a report that color codes each session according to its power consumption. A session is defined as the period from Screen Off to Screen On. In cases when the system is plugged into AC power, the policies are less stringent than when on battery power. While the tool still tracks connected standby activity on AC power, it is more useful to identify unexpected drains on battery, or DC power.”
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