> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/expo/expo/llms.txt
> Use this file to discover all available pages before exploring further.

# expo-battery

> Get battery information and monitor battery state changes

# expo-battery

**Version:** 55.0.6

Provides battery information for the physical device, as well as corresponding event listeners.

## Installation

```bash theme={null}
npx expo install expo-battery
```

## Usage

```typescript theme={null}
import * as Battery from 'expo-battery';
import { useEffect, useState } from 'react';

function App() {
  const [batteryLevel, setBatteryLevel] = useState<number | null>(null);

  useEffect(() => {
    Battery.getBatteryLevelAsync().then(setBatteryLevel);
    
    const subscription = Battery.addBatteryLevelListener(({ batteryLevel }) => {
      setBatteryLevel(batteryLevel);
    });

    return () => subscription.remove();
  }, []);

  return <Text>Battery: {(batteryLevel * 100).toFixed(0)}%</Text>;
}
```

## API Reference

### Methods

<ParamField path="Battery.getBatteryLevelAsync()" type="() => Promise<number>">
  Gets current battery level (0-1)

  ```typescript theme={null}
  const level = await Battery.getBatteryLevelAsync();
  console.log(`${(level * 100).toFixed(0)}%`);
  ```
</ParamField>

<ParamField path="Battery.getBatteryStateAsync()" type="() => Promise<BatteryState>">
  Gets battery charging state

  Returns:

  * `Battery.BatteryState.UNKNOWN`
  * `Battery.BatteryState.UNPLUGGED`
  * `Battery.BatteryState.CHARGING`
  * `Battery.BatteryState.FULL`
</ParamField>

<ParamField path="Battery.isLowPowerModeEnabledAsync()" type="() => Promise<boolean>">
  Checks if low power mode is enabled
</ParamField>

<ParamField path="Battery.getPowerStateAsync()" type="() => Promise<PowerState>">
  Gets complete power state

  ```typescript theme={null}
  const powerState = await Battery.getPowerStateAsync();
  console.log(powerState);
  // {
  //   batteryLevel: 0.75,
  //   batteryState: Battery.BatteryState.CHARGING,
  //   lowPowerMode: false
  // }
  ```
</ParamField>

### Event Listeners

<ParamField path="Battery.addBatteryLevelListener(listener)" type="(listener: (event: BatteryLevelEvent) => void) => EventSubscription">
  Listens for battery level changes

  ```typescript theme={null}
  const subscription = Battery.addBatteryLevelListener(({ batteryLevel }) => {
    console.log('Battery:', batteryLevel);
  });

  // Clean up
  subscription.remove();
  ```
</ParamField>

<ParamField path="Battery.addBatteryStateListener(listener)" type="(listener: (event: BatteryStateEvent) => void) => EventSubscription">
  Listens for battery state changes
</ParamField>

<ParamField path="Battery.addLowPowerModeListener(listener)" type="(listener: (event: LowPowerModeEvent) => void) => EventSubscription">
  Listens for low power mode changes
</ParamField>

## Examples

### Battery Indicator

```tsx theme={null}
import * as Battery from 'expo-battery';
import { useEffect, useState } from 'react';
import { View, Text, StyleSheet } from 'react-native';

function BatteryIndicator() {
  const [batteryLevel, setBatteryLevel] = useState(0);
  const [batteryState, setBatteryState] = useState(Battery.BatteryState.UNKNOWN);

  useEffect(() => {
    async function loadBatteryInfo() {
      const level = await Battery.getBatteryLevelAsync();
      const state = await Battery.getBatteryStateAsync();
      setBatteryLevel(level);
      setBatteryState(state);
    }

    loadBatteryInfo();

    const levelSub = Battery.addBatteryLevelListener(({ batteryLevel }) => {
      setBatteryLevel(batteryLevel);
    });

    const stateSub = Battery.addBatteryStateListener(({ batteryState }) => {
      setBatteryState(batteryState);
    });

    return () => {
      levelSub.remove();
      stateSub.remove();
    };
  }, []);

  const percentage = (batteryLevel * 100).toFixed(0);
  const isCharging = batteryState === Battery.BatteryState.CHARGING;

  return (
    <View style={styles.container}>
      <Text style={styles.percentage}>{percentage}%</Text>
      <Text>{isCharging ? '⚡ Charging' : '🔋 Unplugged'}</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  container: { padding: 20, alignItems: 'center' },
  percentage: { fontSize: 48, fontWeight: 'bold' }
});
```

### Low Battery Warning

```tsx theme={null}
import * as Battery from 'expo-battery';
import { useEffect, useState } from 'react';
import { Alert } from 'react-native';

function useBatteryWarning() {
  useEffect(() => {
    const subscription = Battery.addBatteryLevelListener(({ batteryLevel }) => {
      if (batteryLevel < 0.2) {
        Alert.alert(
          'Low Battery',
          'Battery is below 20%. Please charge your device.'
        );
      }
    });

    return () => subscription.remove();
  }, []);
}
```

## Platform Support

| Platform | Supported              |
| -------- | ---------------------- |
| iOS      | ✅                      |
| Android  | ✅                      |
| Web      | ✅ (Battery Status API) |

## Resources

* [Official Documentation](https://docs.expo.dev/versions/latest/sdk/battery/)
* [GitHub Repository](https://github.com/expo/expo/tree/main/packages/expo-battery)