Make a holding directory on the C drive lets say C:\Holding
Open up Notepad
Paste the following in to the screen
Powercfg /batteryreport
Powercfg /sleepstudy
Powercfg /energy
File....Save As , select File Type "All files", save into your new directory as power.bat
Open an administrator command shell (type cmd in the menu bar, right click, run as Administrator)
Change to the C:\Holding directory
type power, hit return, wait approx. 90 seconds until the tasks have run
You will now have 3 HTML files you can open in a browser to read
Battery-Report
Energy-Report
SleepStudy-Report
These will tell you the battery life, estimates usage etc. of the battery, what is using up power and the status of sleep/hibernation etc.
This will be you first stop to see what is eating power, if you have an issue with the battery etc.