Battery test
Open the page and the readings appear straight away: percent charged, whether the charger is connected, and how long the browser estimates until the battery is full or empty. The values update by themselves when the level or charger changes. Only Chromium browsers (Chrome, Edge, Opera, Samsung Internet) share this data.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Open the page in Chrome or Edge on the device you want to check.
- Read the level and status. Plug in or unplug the charger and watch the values change without reloading.
- The third line switches between Time until full (charging) and Time until empty (on battery).
How it works
The page calls navigator.getBattery() and listens for four events: level change, charging change, and changes of the two time estimates. When one fires it reads the new values. Nothing polls in the background, and nothing is sent anywhere.
Worked example
The browser gives the level as a number from 0 to 1 and times in seconds. A level of 0.874 is shown as 87 %. A charging time of 5400 seconds is 5400 ÷ 60 = 90 minutes, shown as 1 h 30 min. If the browser reports an unknown time (infinity), the page says it is not available.
Tips
- Battery saver modes can change how often the browser updates the readings.
- On a laptop that is always plugged in, the status stays on Fully charged or Charging and no time to empty is shown.
Frequently asked questions
Why does it say my browser is not supported?
Battery Status is only implemented in Chromium-based browsers. Safari and Firefox removed or never shipped it because the readings can be used to track people. Try Chrome or Edge, or check the battery in your system settings.
Why is the time left not available?
The browser reports an unknown time until it has watched the level change for a while. After you plug in or unplug, wait a minute or two and the estimate usually appears. When the battery is already full there is nothing left to charge.
How accurate is the time estimate?
It is the operating system's estimate from the recent rate of change. It jumps around when you start a game or video, so treat it as a rough guide, not a promise.
Does this tell me the battery health or capacity?
No. The browser only exposes the current level, charging state and the two time estimates. Health, cycle count and capacity are in your system's battery settings.