Windows 7 includes a nifty little utility that will automatically scan your laptop and offer advice on how to improve battery life. It also detects devices that might be preventing the laptop from entering a low-power state. Best of all is that it presents everything in an HTML file that you can view using your browser. Here's how to get your own Windows 7 power report.
1. The power report is run using the command prompt and needs to have administrator privileges in order to work. Click on the Start button, select 'All Programs' and, under 'Accessories', right-click 'Command Prompt'. From the list of options that appears, click 'Run as administrator'.
2. A command-prompt window will now appear. Before running the application, make sure the laptop is in the configuration that you would use when relying on the battery. Leave any essential USB devices plugged in -- these will be monitored and included in the power report.
3. The power report doesn't need to be run from a specific folder, so simply type 'powercfg –energy' (leave out the quote marks). An 'Enabling tracing for 60 seconds' message should now appear. When the minute is up, you'll see an indication of how many errors, warnings and general information messages were generated. You'll also be told where to find the full report. In this case, it's in the 'C:\Windows\system32' directory.
4. Close the command-prompt window and, using Windows Explorer, navigate to the folder as detailed in the previous step. Locate the 'energy-report.html' file and double-click it. The full report will now open in a new browser window. At the top, you'll see general information about the laptop, including its name, how many processes were running and whether or not it was plugged in.
5. The interesting details are found further down, under 'Analysis Results'. In this example, it's warning that we're running the laptop on the 'High Performance' plan even when on battery power, and that the laptop isn't set to automatically go into a sleep state after a set period of time. Scroll down further to the 'Warnings' and 'Information' sections, and you'll be offered additional advice on how to improve battery life.