1. Elevate Privilege
Windows 7 Includes a utility that will scan your laptop and look for processes and setting that might be draining unnecessary power. You will need to run it from the command line. Click the Start button, type "cmd" in the search box. right-click the Command Prompt item and choose "Run as administrator".
2. Run the scan
At the command prompt, type "powercfg-energy". Make sure that your laptop is running on battery power, otherwise you'll be testing it in the wrong power usage mode. The test takes 60 second to run and separates energy efficiency issues into errors, warning and 'informational'. If you get no error or warning, you're good to go.
3. Check the report
Otherwise, you will need to check the detailed report for the analysis of the errors and warning. This is written as an HTML file, usually to C:\Windows\System32, but it will tell you where to look in any case. Open it in your browser and decide how much you agree and/or case about the particular recommendations it makes.
4. Tweak the settings
For most of them, it's simply a matter of opening the Power Options section of Control Panel and ticking or unticking the appropriate box for your power plan. Sometimes you may also have background processes running that are preventing certain options from cutting in or that are thrashing the CPU too hard.