Before you think about buying a new battery for your laptop, it’s essential to make sure the battery is really faulty. With a simple command, you can check the condition of the battery yourself without removing it or calling a technician.
Run the diagnostic from the system console
Access the system command
To start, right-click the Start button on your system, located at the bottom left of the screen. In the menu that appears, select “Command Prompt (admin)” or the equivalent option depending on your Windows version.
A black window (console) will then appear. Where you see the path C:\WINDOWS\system32>, type the following command:
bash
Copy code
powercfg -energy
Then confirm by pressing Enter.
Wait for the energy analysis to complete
Windows will now run a full analysis of your system’s power consumption. This may take around a minute. At the end, a message appears telling you where the generated report file has been saved.
For example:
An energy report has been saved to C:\WINDOWS\system32\energy-report.html.
Open the report to view the battery data
Follow the file path
To open this report, you need to browse through your files:
- Go to your main drive (usually called C:).
- Open the folders in this order: Windows > system32.
- Find the file called energy-report.html and double-click it.
It will open in your default web browser.
Interpret the technical data for your battery
Identify the key values
In the HTML report, locate the section called “Battery information”. You’ll see several lines there, but two values are particularly important:
- Design capacity (the maximum capacity the battery had when it was new)
- Last full charge (the current maximum capacity after a full recharge)
Calculate your battery’s health
Here’s how to tell if your battery is worn:
Multiply the ratio between the current capacity and the design capacity by 100.
For example:
- Design capacity: 40 000
- Last full charge: 36 000
- Calculation: (36 000 / 40 000) x 100 = 90%
Your battery has therefore lost 10% of its original capacity, which is still perfectly acceptable.
If you can’t access the report
Sometimes you may not be able to open the HTML file or your system permissions may be limited. In that case, you can use a free diagnostic tool that will directly display the battery wear level, temperature and charge cycles.
Conclusion: a useful check to avoid unnecessary spending
Before replacing a battery, a simple software test can save you time and money. This method only takes a few minutes and gives you a precise estimate of your battery’s remaining life. Remember that battery ageing is normal, but that doesn’t mean it has to be changed at the first signs of weakness.
