Battery Information
View your device battery level, charging status, and estimated time remaining. Works on supported browsers.
How Does the Battery Information Tool Work?
- The tool uses the Battery Status API to read your device's battery information.
- It displays charge level, charging state, and estimated time remaining.
- The display updates in real time as your battery charges or discharges.
- All information comes directly from your operating system through the browser.
How the Battery Status API Works
The Battery Status API (navigator.getBattery()) gives web pages read-only access to four properties from your operating system's power subsystem: level (charge percentage as a decimal between 0 and 1), charging (whether the device is plugged in), chargingTime (estimated seconds until full), and dischargingTime (estimated seconds until empty). The API also fires events when any of these values change, which is how this tool updates in real time without polling.
Browser support is limited. Chromium-based browsers (Chrome, Edge, Opera, Brave) support the API on desktop and Android. Firefox removed it in version 52 after research demonstrated that the precise battery level could be used as a fingerprinting vector — two users on the same network with identical battery percentages and discharge times are likely the same person. Safari has never implemented the API. If this tool reports that battery information is unavailable, your browser has intentionally disabled it.
Understanding Battery Health and Charge Cycles
Every lithium-ion battery degrades over time. A charge cycle is one full discharge from 100% to 0%, or equivalent partial discharges that add up to 100%. Most laptop batteries retain roughly 80% of their original capacity after 500–1000 charge cycles, depending on the chemistry and manufacturer. Apple rates MacBook batteries for 1000 cycles; many Windows laptops target 500.
The Browser Battery API does not expose cycle count or wear level — that data lives in the battery controller firmware and requires native tools to access. On macOS, System Information → Power shows cycle count. On Windows, run powercfg /batteryreport from the command line for a detailed HTML report. On Linux, /sys/class/power_supply/BAT0/ contains raw values. If you notice your battery draining faster than it used to, checking the cycle count is the first diagnostic step.
Tips for Extending Laptop Battery Life
Lithium-ion batteries degrade fastest when kept at very high or very low charge levels for extended periods. If your laptop stays plugged in most of the time, use your manufacturer's battery charge limit feature (available on Lenovo, ASUS, Dell, and newer MacBooks) to cap the charge at 80%. This alone can significantly extend the battery's usable lifespan over years.
Heat is the other major enemy. Running demanding workloads on a laptop sitting on a soft surface that blocks airflow accelerates chemical degradation inside the cells. Using a cooling pad or hard surface helps. Avoid leaving your laptop in a hot car or in direct sunlight while charging. If your battery has swollen visibly, stop using it immediately — that's a sign of internal gas buildup from damaged cells, and continued use is a fire risk.
Frequently Asked Questions
- Why doesn't the battery tool work in my browser?
- The Battery Status API is only supported in Chromium-based browsers (Chrome, Edge, Opera) on desktop. Firefox removed support, and Safari has never supported it due to privacy concerns about battery-based fingerprinting.
- How accurate is the battery percentage?
- The percentage shown comes directly from your operating system's battery driver. It is as accurate as what your OS reports, though actual remaining time can vary based on workload.
- Can this tool check battery health?
- No. The Browser Battery API only provides current charge level, charging state, and time estimates. Battery health diagnostics (cycle count, wear level) require native system tools.