Battery API Browser Support in 2026: What Works and What Doesn't

If you've ever tried to use a battery monitor website and seen "Battery API not supported", you're not alone. The Battery Status API has had a complicated history — embraced by some browsers, rejected by others, and limited even where it works.

Quick reference: support in 2026

Bottom line: desktop Chromium browsers work, Firefox and Safari don't, iOS doesn't.

Why did Firefox remove it?

Firefox removed the Battery Status API in 2017 after researchers showed it could be used as a fingerprinting vector. Even though battery level seems harmless, the combination of charge percentage, charging time, and discharging time at any moment is unique enough to identify a returning visitor across sessions.

Mozilla decided the privacy risk outweighed the limited utility and pulled support entirely.

Why did Safari never add it?

Apple's WebKit team has been consistently conservative about adding APIs that expose hardware state to web pages. Battery API was on their "concerns: privacy" list and never moved past that stage.

Because every browser on iOS is required to use WebKit, this means no browser on iPhone or iPad supports the Battery API.

How Chromium browsers work around the privacy issues

Chrome, Edge, and other Chromium browsers kept the API but added safeguards:

• HTTPS only: the API is unavailable on plain HTTP pages.
• Reduced precision: charge level is rounded.
• Permissions Policy: can be disabled per-site.
• Brave's spoofing: Brave may return random or fixed values.

Code: detecting support cleanly

Here's how to check for the API and handle missing support gracefully:

if ('getBattery' in navigator) {
  navigator.getBattery().then(battery => {
    console.log('Level:', battery.level);
    console.log('Charging:', battery.charging);
    battery.addEventListener('levelchange', () => {
      console.log('New level:', battery.level);
    });
  }).catch(() => {
    showFallbackUI();
  });
} else {
  showFallbackUI();
}

Always wrap getBattery() in a .catch() — some Chromium browsers expose the function but reject the promise based on Permissions Policy.

Available battery properties

When supported, you get a BatteryManager object with:

• level — charge level from 0.0 to 1.0
• charging — boolean, true if plugged in
• chargingTime — seconds remaining until full
• dischargingTime — seconds remaining on battery

And four events: levelchange, chargingchange, chargingtimechange, dischargingtimechange.

What about background tabs?

This is where it gets tricky. Modern browsers aggressively throttle background tabs to save battery. Chrome especially: timers run at 1/min, audio gets paused, and tabs may be fully discarded after several minutes.

For a battery monitor to work reliably in the background, you need two layers:

1. A silent audio loop to prevent the tab from being fully suspended
2. The Notifications API (preferably via a Service Worker) so OS-level alerts fire even if the tab IS suspended

Our Battery Charge Monitor implements both. That's why it actually rings an alarm when you're working in another tab — most browser-based battery tools fail this test.

What to do if your browser doesn't support it

Switch browsers, or use a desktop app

If switching browsers isn't an option, a small desktop app reads battery state directly from the OS. Our free desktop app does this — it sits in the system tray.

OS-native settings

Many laptops have built-in charge limit settings (Lenovo Vantage, Dell Power Manager, ASUS Battery Health Charging). These are the most reliable since they enforce limits at the firmware level.

Will the Battery API ever return to Firefox or Safari?

Probably not in its current form. The W3C Battery Status spec has been considered "feature complete" for years with no momentum to revive it. Until then, web-based battery tools are a Chromium-only world.

Related: The 20-80 Rule Explained · Why You Shouldn't Charge to 100%