How to test your laptop battery and check if it needs replacing

If your laptop's battery life seems to be much worse than it was originally, that's not unusual. Batteries, contrary to popular belief, are consumables and may not last the lifetime of the laptop.

Over time and with lots of use, a battery's capacity will diminish. So if your laptop lasts for considerably less time away from the mains than when you bought it, it's probably time to buy a new one.

That's easier said than done with some laptops: their batteries aren't removable by the user. You can either attempt to disassemble the laptop yourself, assuming you can buy a replacement, or contact the manufacturer to ask where and how to get the battery replaced.

For a very old laptop, it may prove too costly to get a new battery. In which case you'll have to live with poor battery life or budget for a new laptop. If you have an Apple latptop, check out our tips on how to optimise battery life on a MacBook.

Do I need a new laptop battery?

Since Windows 8, there's been a battery usage and performance report built into the operating system. You can use this to measure the capacity of your battery compared to its 'design capacity', which is the capacity you should expect from a brand new battery of the type you're using. This capacity is usually rated in Watt Hours (Wh) and is a statistic we typically quote in laptop reviews.

With use, the capacity of your battery in will decline until it needs to be replaced.

The battery capacity history function, built into Windows 8 and Windows 10, will compare your battery's actual capacity against the design capacity over a period of time, so you can see how well it is performing. If the measured capacity has dropped significantly, this tells you it's time to buy a new battery.

It's also worth noting that leaving a laptop plugged in and turned on for extended periods can cause the battery to deteriorate more quickly. We recommend removing the battery (if that's possible) and putting it back in when you need it. Of course, you should allow enough time to ensure it fully charges.

Some laptops offer a battery saver mode where it charges to a set percentage and no more, even if you leave it plugged in. Many of the big names have such a utility including Dell, Lenovo and others.

Generate a laptop battery report in Windows

To generate a battery report, open up a command prompt by pressing Windows+X and selecting 'command prompt' or in later versions 'Windows PowerShell'.

At the prompt, type: powercfg /batteryreport /output MYFOLDER\mybatteryreport.html

...where MYFOLDER is the full path name to the folder where you would like to save the report, such as c:\Users\Jim\Documents\mybatteryreport.html

The folder(s) you specify must exist already, or you must create them as the command won't make folders for you.

Now press Enter. This will create an HTML file called mybatteryreport.html, which you can read in your favourite browser. Note, this only works on devices fitted with a battery, so don't try if on your desktop or you'll just get an error message.