Knowing the Capacity of Battery Performance in Windows 7
In Windows 7, to know the performance capabilities of a laptop battery or more generally how to make your laptop more efficient from an energy standpoint, just run the following command from the Command Prompt (the command that we are reporting should be execute by an user who has administrative rights on the workstation, which is a user who belongs to the local Administrators group of Windows 7. For your convenience, you should run the command in a temporary folder such as C: \ Temp): powercfg -energy
After few minutes, will be created the Energy-report.html file report in the same folder where you ran the command powercfg -energy. Within the file Energy-report.html you can find several suggestions on how to improve the energy performance of your laptop. In particular, within the section Battery: Battery Information, you can know the battery capacity (Design Capacity) and its charge level (Last Full Charge). If the value reported in Last Full Charge should be smaller than half the value reported in Design Capacity, than it is time to buy a new battery!