Every laptop battery slowly wears out — but how worn is yours, really? Windows keeps a detailed battery report that repair shops quietly use before quoting you a replacement. You can generate the same report free in two minutes, and read it with the method below.

1. Generate the battery report

Right-click the Start button and open Terminal (Admin) or Windows PowerShell (Admin). Type this command and press Enter: powercfg /batteryreport. Windows saves a file called battery-report.html, usually in C:\Users\your-name. Open it in any browser.

2. Read the only two numbers that matter

In the Installed batteries section, compare DESIGN CAPACITY (what the battery held when new) with FULL CHARGE CAPACITY (what it holds now). Example: design 50,000 mWh, full charge 35,000 mWh means your battery is at about 70% health. Above 80% is healthy; 60–80% is worn but usable; below 60% explains sudden shutdowns and 1-hour battery life — replacement is genuinely due.

3. Check the cycle count

The same section shows CYCLE COUNT — how many full charges the battery has lived through. Most laptop batteries are rated for 300–500 cycles before noticeable wear, and 800–1,000 before they are truly tired. A 3-year-old laptop with 900 cycles and 65% health is normal ageing, not a defect.

4. Squeeze more life from a worn battery

Before spending money: turn on Battery saver (Settings → System → Power & battery), lower screen brightness (the biggest single drain), and check the report's Recent usage and the Settings battery page to find which app eats power in the background. In Power & battery settings, also set the screen to turn off sooner on battery.

5. If you mostly use the laptop plugged in

Constant 100% charging wears batteries faster. Many brands offer a charge limit in their own app or BIOS — Lenovo Vantage, Dell BIOS, ASUS Battery Health Charging, HP BIOS — set it to stop at 80% if the laptop lives on a desk. This one setting can add a year or more to battery life.

Safety warning: If your laptop's battery is swollen — the touchpad bulging, keys lifting, or the base rocking on a flat table — stop using it on your lap, do not press it down, and get it replaced promptly. A swollen battery is a fire risk, not just a weak one.

6. Buying a replacement battery

Match the exact model number printed on the old battery, and prefer the laptop brand's own service centre or a reputable seller — the cheapest no-name batteries often report fake capacities and fail within months. After installing, charge fully, use it down to about 10% once, and charge fully again so Windows relearns the real capacity.

Frequently asked questions

Is 70% battery health bad?

It is worn but normal for a 2–4 year old laptop. You will get roughly 70% of the original backup time. Replacement becomes worthwhile below about 60%, or if the laptop shuts down suddenly.

Why does my laptop shut down at 20% battery?

A worn battery's voltage collapses early, so the percentage reading lies. The battery report's full-charge capacity will confirm the wear; recalibration helps the reading, replacement fixes the cause.

Should I remove the battery when using the laptop plugged in?

On modern laptops, no — use the brand's 80% charge-limit setting instead. Removing batteries is neither needed nor possible on most slim models.