I just found something really useful in Windows 8 (Shock!) I’ve been worried about the performance of my laptop battery and though I’d see what was out there to check it out. I found that Win8 has a built in report for this which can be run from this command:
powercfg /batteryreport /output %USERPROFILE%\Desktop\battery_report.html
This saves an .HTML file to your desktop with more info on your battery than you thought possible. Good stuff MS.