Windows 7 does a great job managing power consumption, preserving and extending battery life, in comparison to previous versions. Now it also includes a command-line tool called Powercfg that can help you to analyze your system for common energy efficiency and battery life problems. This tool is more commonly used by manufactures and developers to create drivers, but it can be easily used by anyone and it can provide really useful information and more importantly is information that we can use to determine if it time to replace the laptop battery. To run this tool:

  1.  Go to Start, in the search box type cmd, right-click it and select Run as Administrator.

  2.  From the Windows Command Prompt type powercfg -energy. This command will initiate a diagnose, observing the system behavior, which it takes about one minute, then it will dump all the information collected to a file named energy-report.html that it will be located in your C drive.

  3.  Double-click to open the energy-report.html in your default web browser.

  4.  In the energy report you can find very useful information like: Errors, Warnings and Informational messages, all related to energy. We are going to focus in one parameter, look for Battery: Battery Information — scroll down the page and it will be almost at the end –.

There you will see two numbers the Design Capacity and Last Full Charge. The higher the Last Full Charge is to the Design Capacity, it means that your battery is doing OK, after a period of time (e.g. one year or two years), you’ll notice that the Last Full Charge number will start decreasing and that essentially is saying that your battery is not lasting as long, or you are not charging it to its full capacity all the time. So what you want to do here is to plug your laptop in for a good 12 hours, make sure that it is a full charge as possible, take another report and see where is at. If the Last Full Charge number falls below 50% in relation to the Design Capacity, it is probably the time to replace the laptop battery. I hope this was helpful. If you have other methods to check when to know if the laptop battery went bad and it needs to be replaced, let us know in the comments below. All content on this site is provided with no warranties, express or implied. Use any information at your own risk. Always backup of your device and files before making any changes. Privacy policy info.