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    Battery Status API

    The Battery Status API, more often referred to as the Battery API, provides information about the system's battery charge level and lets you be notified by events that are sent when the battery level or charging status change. This can be used to adjust your app's resource usage to reduce battery drain when the battery is low, or to save changes before the battery runs out in order to prevent data loss.

    The Battery Status API extends window.navigator with a navigator.getBattery method returning a battery promise, which is resolved in a BatteryManager object providing also some new events you can handle to monitor the battery status.


    In this example, we watch for changes both to the charging status (whether or not we're plugged in and charging) and for changes to the battery level and timing. This is done by listening for the chargingchange, levelchange, chargingtimechange, dischargingtimechange events.

    navigator.getBattery().then(function(battery) {
      console.log("Battery charging? " + (battery.charging ? "Yes" : "No"));
      console.log("Battery level: " + battery.level * 100 + "%");
      console.log("Battery charging time: " + battery.chargingTime + " seconds");
      console.log("Battery discharging time: " + battery.dischargingTime + " seconds");
      battery.addEventListener('chargingchange', function() {
        console.log("Battery charging? " + (battery.charging ? "Yes" : "No"));
      battery.addEventListener('levelchange', function() {
        console.log("Battery level: " + battery.level * 100 + "%");
      battery.addEventListener('chargingtimechange', function() {
        console.log("Battery charging time: " + battery.chargingTime + " seconds");
      battery.addEventListener('dischargingtimechange', function() {
        console.log("Battery discharging time: " + battery.dischargingTime + " seconds");

    See also the example in the specification.


    Specification Status Comment
    Battery Status API Working Draft Last Call Working Draft.

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support 38 Supports the deprecated navigator.battery.
    10 (10) moz [1]
    16 (16) (without prefix) [2]
    Not supported 25 Not supported
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support Not supported 39 [3]

    Supports the deprecated navigator.battery
    10.0 (10) moz [1]
    16.0 (16) (without prefix) [2]

    Not supported 25 [3] Not supported


    [1] Disabled by default in Firefox 10.0, but can be enabled setting the preference dom.battery.enabled to true. Starting with Firefox 11.0, mozBattery is enabled by default.

    [2] The Battery API is currently supported on Android, Windows, and Linux with UPower installed. Support for MacOS is available starting with Gecko 18.0 (Firefox 18.0 / Thunderbird 18.0 / SeaMonkey 2.15).

    [3] Values for BatteryManager.chargingTime and BatteryManager.dischargingTime are always equal to Infinity.

    See also

    Document Tags and Contributors

    Last updated by: SpencerG,