Use a hidden Windows 7 report to monitor your laptop’s power efficiency

One of the biggest complaints about Vista was that it tended to drain laptop batteries with greater abandon than XP. While we don’t expect Windows 7 to offer huge improvements in that department, Microsoft is putting more of that control in the users’ hands.
In Windows 7, you can observe your PC’s power efficiency and tweak settings to get the most out of your battery and the best balance between performance and endurance. Doing so is a little techie, but it’s not hard.
In the Start menu, type in cmd. Then, when the cmd.exe icon appears, right-click it, and choose “Run as an administrator.” At the command line that pops up, type powercfg –energy and hit Enter. At this point, Windows 7 will scan your system (it will take a minute or two) and publish a report in the folder indicated by the command line. Follow the path indicated to the file—it’ll be an HTML document—and look through the suggestions. Here's what we saw:

In our report, for instance, we got a handful of pink error messages stating that our power settings weren’t set for optimal battery life. Those are pretty easy to fix: Go to Control Panel > Hardware and Sound > Power Options, then select which plan you’d like and click Edit Plan Settings. From there, you can tweak to your heart’s content. We also got a handful of yellow warning messages, such as “Power Policy: Disk timeout is long (On Battery).” Our hard drive was set to turn off after 1,000 minutes, but this warning suggests keeping that time to less than 30 minutes so that if the hard drive doesn’t need to be spinning, it can turn off after a given amount of time. The trade-off (and yes, there’s always a trade-off) is that when you choose a task that requires it to spin back up again, it can be slow in doing so.
This is a good report to run, so that, at the very least, you can get an idea of which settings affect power consumption. Once you have that knowledge, tweaking those settings is pretty simple.