Battery

Battery level, charging state, and low power mode

One.Battery reports the battery level, charging state, and low power mode on iOS and Android, with live change listeners and hooks. It has getLevel(), getState(), getPowerState(), isLowPowerModeEnabled(), isAvailable(), addLevelListener(fn), addStateListener(fn), and addLowPowerModeListener(fn).

import { One, useBatteryLevel } from 'one'

const level = await One.Battery.getLevel()
const state = await One.Battery.getState()
const power = await One.Battery.getPowerState()

export function Level() {
  const level = useBatteryLevel()
  return <>{level < 0 ? 'unknown' : `${Math.round(level * 100)}%`}</>
}

getLevel() resolves a number between 0 and 1, or -1 when the device does not report a level. getState() resolves 'unknown', 'unplugged', 'charging', 'full', or 'notCharging' (Android only). getPowerState() resolves { batteryLevel, batteryState, lowPowerMode } in one read. isLowPowerModeEnabled() reports Power Saver mode on Android and Low Power Mode on iOS. isAvailable() is synchronous: true on Android and physical iOS devices, false on iOS simulators.

Each listener receives one payload object: { batteryLevel }, { batteryState }, or { lowPowerMode }. Listeners return { remove() }. On Android the level event fires on significant changes only; on iOS it fires on drops of one percent or more, at most once per minute. The hooks useBatteryLevel(), useBatteryState(), useLowPowerMode(), and usePowerState() publish the one-shot read plus live updates.

On web, the Battery Status API supplies live level and charging state where the browser has it; without it reads resolve 1, 'unknown', and false, and listeners never fire. Android battery optimization (doze-mode exemption) is not part of this module.