The Battery API may not be supported by your browser. Try Chrome or Edge on Android. On iOS, the Battery API is not available. Desktop browsers may also have limited support depending on the platform.

Minor differences between the browser reading and system tray are normal. Both sources use the same underlying battery data but may calculate or display it slightly differently.

The Battery API fires events when the state changes, but there may be a brief delay. Try refreshing the page. If the issue persists, the browser may have limited Battery API support.

Battery time estimates are based on recent usage patterns. They become more accurate over time as the system gathers more data. Drastic changes in usage will make estimates less reliable.

Different apps and operating systems may calculate battery percentage differently based on voltage curves and calibration. The Battery API provides the browser's reading, which should be close to but may not exactly match your system battery indicator.

The test only reads battery status information — it doesn't actively drain the battery. The page itself uses minimal power since it's mostly displaying static information updated periodically.

The Battery API doesn't expose detailed health metrics like capacity degradation. It only shows current charge level and charging status. For detailed battery health information, check your device's built-in battery settings or use manufacturer-specific diagnostic tools.

This test shows real-time battery status, not battery life over time. To test battery life, note the starting percentage, use your device normally for a set period, then check the percentage drop. Repeat under different usage scenarios for comparison.

The Battery API fires 'levelchange' and 'chargingchange' events, but the update frequency varies by browser and device. The test listens for these events and updates when they fire. Some devices may take a few seconds to reflect charging state changes.

Yes, if the browser supports the Battery API. Most modern browsers on laptops support it, but desktop PCs with external power supplies may show limited information (always 'charging' at 100%). Some browsers disable the API for privacy reasons.