# What is draining my Android battery?

To find a battery drain, look at the rate (milliamp-hours per hour) over a long enough window, not just the total, and look for apps that stay awake: wakelocks, sensor polling and background jobs.

## Why the battery screen can mislead

- Android's statistics cover the time since the last charge, so a long window and a short window are not comparable.
- Totals hide the story: an app that ran for ten minutes at high power and one that quietly runs all day can use the same mAh.
- Right after charging the window is only seconds long. A rate computed from it is meaningless, and slimdroid says so instead of showing one.

## What usually causes a drain

- Apps that hold a wakelock and stop the phone from sleeping.
- Sensors polled constantly: location, motion and other sensors, often by background services.
- Background jobs and sync that run far more often than needed.
- Preinstalled services that you never use but cannot see.
- A weak mobile signal: the radio works harder to stay connected.

## How to measure it

```
adb shell dumpsys batterystats            # per-app power since last charge
adb shell dumpsys deviceidle whitelist    # apps exempt from Doze
adb shell dumpsys sensorservice           # who is using sensors
```

The [slimdroid tool](https://slimdroid.com/app) reads these dumps, converts them to mAh per hour and lists sensor pollers and Doze-exempt apps, with the app's purpose beside each one. Scan after the phone has been unplugged for several hours for a meaningful rate.

## What to do about it

1. Set heavy background apps to **Restricted** or **Optimised** in Settings > Apps > Battery.
2. Revoke location and sensor permissions that an app does not need.
3. Disable preinstalled apps you never use ([guide](https://slimdroid.com/guides/debloat-android-without-root)).
4. Compare a scan before and after to confirm the change worked.

### How much overnight drain is normal?

A healthy phone on standby loses only a few percent overnight. If it loses ten percent or more, something is keeping it awake.

### Does Doze exemption matter?

Yes. Apps exempt from Doze can run in the background while the phone is idle, so each one on that list is a possible drain.

## Related guides

- [Android phone slow? Find what is slowing it down](https://slimdroid.com/guides/fix-slow-android-phone)
- [Android privacy: which apps collect data and how to limit them](https://slimdroid.com/guides/android-privacy-telemetry-apps)
- [How to debloat an Android phone without root](https://slimdroid.com/guides/debloat-android-without-root)
- [Android slow after an update: why it happens and what to do](https://slimdroid.com/guides/android-slow-after-update)