How Healthy Your Battery is on Your Laptop

Find out How Healthy Your Battery is on Your Laptop 

Windows 7 has a feature through which we can find out exactly how much
battery you are actually getting from your Laptop battery, i.e. its efficiency,
maximum charge potential.
1. Open command prompt by typing "cmd" in your start menu & opening it with administrator privileges.

2. Type "powercfg –energy" into the command prompt & press Enter.

3. The command enables tracing for 60 seconds & would collect all the data
after observing the system behavior.

4. After analysis it would generate a report.

5. The energy report is generated in HTML format in the directory shown in
the command prompt.
        Cmd Prompt Address\energy-report.html by default.

6. In the HTML file, scroll to the end till you get information like this:

This shows the battery ID, Manufacturer name, Chemistry, Design capacity
and most importantly the last full charge.
So as above screenshot Dell Studio 15 battery has design capacity of
5200 and now it's giving max full charge of 3565 that counts its efficiency
to around 70% it has degraded around 30% in 6 months.