Identifying power management issues in Windows 7

A few weeks back my friend and colleague Garry Martin alerted me to an enhanced battery indicator for Windows Vista and 7 (BatteryBar). Normally, I wouldn’t want to use something that installed a big button in the notification area but this is actually a pretty useful enhancement over the standard power icon (and better looking than many of the OEM-provided versions). Not only can I see how much battery charge I have left but BatteryBar shows information such as capacity, charge rate, battery wear, etc.

It’s worth knowing though, that for tweaking power settings, Windows 7 users have another tool at their disposal – the powercfg.exe command line tool. This tool exists in Vista too but in the Windows 7 beta there is a new switch (/energy) that generates a Power Efficiency Diagnostics Report (saved to %systemroot%\system32\energy-report.html).

In addition to providing details of the system used to generate the report, the report highlights errors, warnings and information about a system’s current state to identify: USB devices that are not suspending (and therefore preventing the CPU from managing power effectively); processes that are requesting a small timer resolution; processes with high CPU utilisation; as well as information about the power plan, battery and processor power management capabilities.

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