Battery Manager

Battery Manager is an Android app written in Kotlin with XML layouts. It shows live battery information, tracks recent app usage, and can run a foreground service that warns the user when the phone is almost fully charged.

The project is built as a native Android app with ViewBinding, Material components, Lottie animation, and a circular progress indicator for the battery level.

Features

• Live battery percentage with animated circular progress
• Battery voltage, temperature, technology, and plugged/unplugged status
• Battery health messages for good, cold, overheat, over-voltage, and dead states
• Drawer menu with app usage navigation
• Foreground service that keeps a battery notification active
• Alarm sound and vibration when the battery level goes above 97%
• 24-hour app usage list with app names, icons, usage percentages, and time spent
• Splash screen with Lottie animation and rotating messages
• Service state saved with SharedPreferences

Tech Stack

• Kotlin
• Android XML layouts
• Gradle / Android Gradle Plugin
• ViewBinding
• AndroidX AppCompat
• ConstraintLayout
• Material Components
• Lottie
• CircularProgressBar by Mikhael Lopez

Project Structure

.
+-- app/
|   +-- src/main/
|   |   +-- AndroidManifest.xml
|   |   +-- java/com/alirahimi/batterymanager/
|   |   |   +-- activity/
|   |   |   |   +-- SplashActivity.kt
|   |   |   |   +-- MainActivity.kt
|   |   |   |   +-- UsageBatteryActivity.kt
|   |   |   +-- adapter/
|   |   |   |   +-- BatteryUsageAdapter.kt
|   |   |   +-- model/
|   |   |   |   +-- BatteryModel.kt
|   |   |   +-- services/
|   |   |   |   +-- BatteryAlarmService.kt
|   |   |   +-- sharedPreferences/
|   |   |   |   +-- SharedPreferencedManager.kt
|   |   |   +-- utils/
|   |   |       +-- BatteryUsage.kt
|   |   +-- res/
|   |       +-- layout/
|   |       +-- drawable/
|   |       +-- raw/
|   |       +-- values/
+-- build.gradle
+-- settings.gradle
+-- gradle.properties
+-- README.md

Main Components

Component	Purpose
SplashActivity	Displays the splash screen and opens the main screen after a short delay.
MainActivity	Shows live battery status and controls the navigation drawer.
UsageBatteryActivity	Displays recent app usage in a RecyclerView.
BatteryUsage	Reads app usage stats for the last 24 hours.
BatteryUsageAdapter	Groups usage entries by package and renders app name, icon, time, and percentage.
BatteryAlarmService	Foreground service that updates a persistent battery notification and triggers an alarm near full charge.
SharedPreferencedManager	Stores whether the battery alarm service is enabled.
BatteryModel	Simple model for package name, usage percent, and usage time.

Permissions

The app declares these permissions in AndroidManifest.xml:

Permission	Used For
FOREGROUND_SERVICE	Running BatteryAlarmService as a foreground service.
QUERY_ALL_PACKAGES	Resolving installed app names and icons for the app usage list.
VIBRATE	Vibrating the phone when the near-full-charge alarm is triggered.

The usage screen also relies on Android Usage Access. If usage stats are unavailable, the app opens the system Usage Access settings screen so the user can grant access.

How It Works

1. SplashActivity shows the startup screen, then launches MainActivity.
2. MainActivity registers an ACTION_BATTERY_CHANGED receiver.
3. The receiver updates battery percentage, voltage, temperature, battery technology, plugged status, and health state.
4. The circular progress bar changes color based on charge level: red for low, yellow for medium, and green for high.
5. The drawer switch stores the service state in SharedPreferences.
6. When enabled, BatteryAlarmService starts as a foreground service and keeps a notification updated with current battery status.
7. If battery level is above 97%, the service plays the default notification sound and vibrates the device.
8. UsageBatteryActivity reads usage stats from the last 24 hours and displays each app with usage time and percentage.

App Usage Calculation

The app usage page calculates percentages from foreground time during the last 24 hours:

item.totalTimeInForeground / totalForegroundTime * 100

This means the list represents relative foreground usage time, not exact battery drain reported by Android's battery settings.

Requirements

• Android Studio
• JDK 8 or newer
• Android SDK with compile SDK 32
• Android device or emulator running Android 5.0+ because minSdk is 21

Project configuration:

Setting	Value
Application ID	com.alirahimi.batterymanager
Min SDK	21
Target SDK	32
Compile SDK	32
Version	1.0
Android Gradle Plugin	7.1.3
Kotlin Plugin	1.5.30

How to Run

Open the project in Android Studio and let Gradle sync. Then run the app configuration on an emulator or physical Android device.

You can also build from the terminal:

./gradlew assembleDebug

Install the debug build on a connected device:

./gradlew installDebug

Notes

• The app uses ACTION_BATTERY_CHANGED, which is a sticky broadcast and does not require a custom polling loop.
• The near-full-charge alarm currently triggers when battery level is greater than 97.
• Usage stats require user approval from Android settings.
• QUERY_ALL_PACKAGES is a sensitive permission on newer Android versions and should be reviewed before publishing to Google Play.
• The repository includes IDE and release-output files; they are not required to understand the source code.

Possible Improvements

• Add a configurable alarm threshold instead of the fixed 97% value
• Add a notification action to stop the foreground service
• Register and unregister battery receivers with lifecycle cleanup
• Use UsageStatsManager defensively when total foreground time is zero
• Replace QUERY_ALL_PACKAGES with a narrower package visibility strategy when possible
• Add unit tests for usage grouping and time formatting
• Add screenshots or a demo GIF to the README