🔋 Battery Status Detector

Test the Battery Status API in your browser. Historically used for fingerprinting, this API is now deprecated in most modern browsers for privacy reasons.

Checking battery status...

Charging

Charging Time

Discharging Time

API Status

Privacy Implications

The Battery Status API was historically used for fingerprinting. Even though battery level is shown as a percentage, combined with charging status and time remaining, it could create a unique signature to track users across websites. Modern browsers now block or limit this API to protect user privacy.

The Battery Status API allows websites to access information about the device's battery:

Battery level - Percentage from 0 to 1 (0% to 100%)
Charging status - Whether the device is plugged in
Charging time - Estimated time until fully charged (in seconds)
Discharging time - Estimated time until battery depletes (in seconds)

Browser Support History

Firefox - Supported until 2016, then removed for privacy
Chrome - Supported until 2019, then deprecated
Safari - Never supported
Edge (Chromium) - Deprecated since 2019
Opera - Deprecated since 2019

// Original Battery Status API usage
navigator.getBattery().then(battery => {
    console.log('Battery level:', battery.level * 100 + '%');
    console.log('Charging:', battery.charging);
    console.log('Charging time:', battery.chargingTime + 's');
    console.log('Discharging time:', battery.dischargingTime + 's');

    // Listen for changes
    battery.addEventListener('levelchange', () => {
        console.log('Battery level changed:', battery.level);
    });
});
                

The Battery Status API became a significant privacy concern because it enabled precise user tracking:

How Battery Data Was Used for Fingerprinting

Unique Combinations: Battery level (0-100%) + charging time creates thousands of possible combinations
Cross-Site Tracking: Users could be tracked across websites without cookies
Short-Term Tracking: Battery values change slowly enough to track users for 30-60 minutes
Combined Fingerprinting: Battery data enhanced other fingerprinting techniques

Real-World Abuse Examples

In 2015, researchers demonstrated that two websites could correlate battery levels to identify the same user visiting both sites. A user with battery at 47% and charging time of 1832 seconds would have the same values on both sites for several minutes, enabling cross-site tracking.

Browser Vendor Response

Firefox (2016) - First to remove the API entirely
Chrome (2019) - Deprecated the API, returns hardcoded values
Safari - Never implemented the API

// Privacy attack example (no longer works in modern browsers)
async function fingerprintBattery() {
    const battery = await navigator.getBattery();

    // Create unique ID from battery state
    const batteryFingerprint = {
        level: Math.floor(battery.level * 100),
        charging: battery.charging,
        chargingTime: battery.chargingTime,
        dischargingTime: battery.dischargingTime
    };

    // Send to tracking server
    const fingerprintId = btoa(JSON.stringify(batteryFingerprint));
    console.log('Battery fingerprint:', fingerprintId);

    // This fingerprint could track users for 30-60 minutes
    return fingerprintId;
}
                

You can detect if the Battery Status API is supported in your browser:

// Feature detection
if ('getBattery' in navigator) {
    console.log('Battery Status API is supported');

    navigator.getBattery().then(battery => {
        // Check if values are real or spoofed
        const isRealData =
            battery.level !== 1.0 ||
            battery.charging !== true ||
            battery.chargingTime !== Infinity ||
            battery.dischargingTime !== Infinity;

        if (isRealData) {
            console.log('Battery API returns real data');
        } else {
            console.log('Battery API blocked (returns default values)');
        }
    });
} else {
    console.log('Battery Status API not supported');
}
                

Default Values in Blocked Browsers

Modern Chrome/Edge return these hardcoded values:

level: 1.0 (100%)
charging: true
chargingTime: Infinity
dischargingTime: Infinity

These values ensure existing code doesn't break while preventing fingerprinting.

Here's how to safely check battery status in 2025:

async function checkBatteryStatus() {
    // Check if API exists
    if (!('getBattery' in navigator)) {
        return {
            supported: false,
            message: 'Battery Status API not supported'
        };
    }

    try {
        const battery = await navigator.getBattery();

        // Check if returning real or default values
        const isBlocked =
            battery.level === 1.0 &&
            battery.charging === true &&
            battery.chargingTime === Infinity &&
            battery.dischargingTime === Infinity;

        if (isBlocked) {
            return {
                supported: true,
                blocked: true,
                message: 'Battery API blocked for privacy'
            };
        }

        // Real battery data
        return {
            supported: true,
            blocked: false,
            level: Math.floor(battery.level * 100),
            charging: battery.charging,
            chargingTime: battery.chargingTime,
            dischargingTime: battery.dischargingTime
        };
    } catch (error) {
        return {
            supported: false,
            error: error.message
        };
    }
}

// Usage
checkBatteryStatus().then(result => {
    console.log('Battery Status:', result);
});
                

Event Listeners

// Listen for battery changes (if API is available)
navigator.getBattery().then(battery => {
    battery.addEventListener('levelchange', () => {
        console.log('Battery level changed:', battery.level);
    });

    battery.addEventListener('chargingchange', () => {
        console.log('Charging status changed:', battery.charging);
    });

    battery.addEventListener('chargingtimechange', () => {
        console.log('Charging time changed:', battery.chargingTime);
    });

    battery.addEventListener('dischargingtimechange', () => {
        console.log('Discharging time changed:', battery.dischargingTime);
    });
});
                