Build a Battery Usage App with React Native and RapidNative

Your team is testing a mobile workflow when someone notices the battery drops unusually fast. The operating system identifies a few likely contributors, but it doesn't explain whether the drain comes from your app's foreground work, background sync, location requests, or a device-specific behavior. A well-designed battery usage app can turn that vague complaint into actionable evidence, but building one with React Native requires more than displaying a battery percentage.

The difficult parts are platform differences, limited background execution, imperfect attribution, and privacy. RapidNative can help you move quickly from a dashboard concept to an exported React Native interface, while native modules and disciplined data collection determine whether the result behaves reliably in production.

Why Build Your Own Battery Usage App

A founder testing a recording product may only need one answer before starting a session: does the phone have enough charge? A development team debugging unexpected drain needs a different answer: what happened while the screen was off, which workflow was active, and did the app's behavior differ between an idle session and a recording session?

Built-in tools are useful starting points. On iPhone, users can open Settings, tap Battery, then tap View All Battery Usage to inspect percentage-based usage for each app across the last eight days, along with daily app and system activity in Apple's battery usage guide. That view makes battery diagnostics accessible without a third-party utility, and it distinguishes activity associated with foreground and background use.

Android provides a different consumer workflow. Battery usage views are generally located under Settings > Battery or Battery and device care > Battery, where apps are ranked by consumption since the last full charge. Some devices also offer a View details control for app-specific battery settings, as described in this Android battery usage walkthrough.

Where a custom monitor earns its place

A product-specific monitor becomes valuable when the operating system's summary doesn't match the question your team needs to answer.

• Workflow diagnostics: Record battery state before and after a camera session, navigation flow, upload, or media playback test.
• Custom alerts: Notify a tester when charging stops, the device reaches a low state, or a monitored workflow behaves differently from its baseline.
• Operational context: Store app state, screen state, network condition, and feature flags alongside battery readings, while clearly separating observed data from estimated attribution.
• Support tooling: Give QA and support teams a repeatable way to collect diagnostics without asking users to interpret system menus.

A ranking alone doesn't prove inefficiency. Roundups repeatedly identify apps such as Facebook, Instagram, YouTube, Uber, Google Maps, Gmail, TikTok, and Netflix as frequent high-drain entries, but aggregate rankings usually don't separate heavier foreground usage from background drain. Your app should therefore present correlation as correlation, not proof that an app is wasteful.

Practical rule: Build for a defined investigation, not an imaginary universal battery score.

Setting Up Your RapidNative Project

Start with a small screen model rather than a large feature list. A useful first version has a current status card, a trend chart, a recent events list, and a diagnostics screen that explains what the app can and cannot observe. That structure keeps the interface understandable for founders and PMs while leaving clear seams for native battery integrations.

Use RapidNative to sketch those screens from a prompt, image, or product document, then inspect the generated React Native structure before adding platform code. Its workflow is suited to live interface iteration and shareable previews, while the battery layer still belongs in a deliberate native integration boundary. The React Native application creation guide is a useful reference for organizing that initial project flow.

Keep the project boundary clean

Create a feature-oriented structure such as:

• battery/, for the JavaScript or TypeScript interface and platform adapter
• storage/, for normalized readings and retention rules
• charts/, for data transformation and rendering
• diagnostics/, for permissions, platform capability, and collection status
• screens/, for dashboard and detail views

For a managed Expo project, expo-battery can provide a convenient starting point for basic device status. A project that needs deeper native behavior may instead use a battery package such as react-native-battery, a custom native module, or an Expo development build with the required configuration. Don't choose a library solely because its API is short. Check whether it supports the platforms, event types, build workflow, and background behavior your product needs.

Rapid iteration is useful here, but it can hide native assumptions. Test a real device early, verify that the package is included in the generated native project, and keep the JavaScript-facing contract stable:

type BatterySnapshot = {
  level: number | null;
  state: "charging" | "full" | "unplugged" | "unknown";
  capturedAt: string;
  source: "ios" | "android";
};

The nullable level matters because a device or simulator may not expose a trustworthy value. If you're evaluating picking the right development partner, ask specifically about native module ownership, release signing, device testing, and long-term maintenance rather than only asking for a polished prototype.

Add a simple mock provider so designers and product stakeholders can review the dashboard without waiting for native events.

Implementing Platform Battery APIs

React Native should expose a consistent application contract, but it shouldn't pretend iOS and Android expose identical battery capabilities. The shared layer can normalize level, charging state, timestamps, and errors. The native adapters should retain platform-specific metadata and clearly label values that are estimates.

On iOS, UIDevice provides battery-related properties after battery monitoring is enabled. A native module can enable monitoring, read batteryLevel and batteryState, and subscribe to battery state or level change notifications. The JavaScript wrapper should remove observers when the subscription ends and should return an explicit unknown state when the device doesn't provide a usable reading.

A Swift-style implementation can follow this shape:

UIDevice.current.isBatteryMonitoringEnabled = true

let level = UIDevice.current.batteryLevel
let state = UIDevice.current.batteryState

NotificationCenter.default.addObserver(
  forName: UIDevice.batteryLevelDidChangeNotification,
  object: nil,
  queue: .main
) { _ in
  // Resolve the current snapshot and emit it to JavaScript.
}

Don't sample aggressively from JavaScript timers and assume the timer represents real device history. Timers pause or drift when the app is suspended, and iOS controls when background work can run. Treat an event-driven reading as a point-in-time observation, not as a guarantee that every intermediate change was captured.

Android needs a different adapter

Android's BatteryManager can expose current battery properties, while a BroadcastReceiver can receive system battery change broadcasts. The receiver should be registered and unregistered according to the host lifecycle, and the module should avoid retaining an Activity reference after the screen is gone.

A Kotlin-style read looks like this:

val manager = context.getSystemService(Context.BATTERY_SERVICE)
        as BatteryManager

val level = manager.getIntProperty(
    BatteryManager.BATTERY_PROPERTY_CAPACITY
)

For state changes, register a receiver for Intent.ACTION_BATTERY_CHANGED, read the level and status extras, then map them to the shared TypeScript model. Some values are unavailable or manufacturer-dependent, so return null or "unknown" rather than displaying false precision.

Android's official Battery Historian documentation describes a developer-oriented workflow for examining device battery data and investigating a specific app by package name. That makes it useful for validating app behavior, but it doesn't mean a consumer-facing React Native app can access every system-level metric directly.

NIST's model provides the right mental model for attribution. It decomposes power into components such as CPU, display, graphics, GPS, audio, microphone, and Wi-Fi, then relates subsystem usage to an application or process in its app-level power estimation publication. In production, store the raw observation, collection context, and confidence separately. Android's built-in estimates can rely on manufacturer-supplied power profiles and may be inaccurate, a limitation noted in the AccuBattery Google Play listing.

Creating the Usage Data Visualization

A chart becomes useful when it answers a question quickly. “Battery level changed” is not enough. A tester wants to know whether the decline followed a recording session, whether charging interrupted the trend, or whether the app lacked fresh observations while suspended.

Use a normalized record rather than storing chart-specific objects:

type UsagePoint = {
  capturedAt: string;
  level: number | null;
  state: string;
  appState: "active" | "inactive" | "background" | "unknown";
  workflow?: string;
};

Keep timestamps in a consistent format, sort them before rendering, discard malformed points, and avoid interpolating a straight line across a long collection gap. A visible gap tells the truth about platform scheduling. A fabricated continuous line suggests certainty you don't have.

Choose charts for decisions

A line chart works for a battery trend, but it should include charging-state markers and collection gaps. A bar chart can compare named workflows, provided the app has enough context to avoid confusing time spent with power inefficiency. A gauge is suitable for current state, but it shouldn't imply battery health or remaining runtime unless you have a defensible measurement model.

Chart libraries such as react-native-chart-kit and victory-native can handle rendering, but the expensive work should happen before rendering. Transform raw records into a compact view model, memoize the result, and keep the number of points shown on a small screen manageable. Use accessible labels so a screen reader can describe the time, level, and state without relying on color alone.

For teams designing broader energy dashboards, the HighFlow Energy monitoring guide offers useful context on presenting consumption information as a monitoring experience. The same design principle applies here: show the observation, its time context, and the action it supports.

Sampling needs restraint. An interval created while the app is open can support a live preview, but it won't continue reliably after suspension. Persist readings locally, batch writes where practical, and make the UI show the last captured time. The React Native guide to data-driven lists, charts, and dashboards can help with the presentation layer, but it won't remove operating-system scheduling limits.

Handling Permissions and Background Tasks

Background collection is where many battery monitoring prototypes become misleading. iOS and Android may both show a current battery value, but neither promises that your JavaScript timer will run continuously after the user leaves the app.

On iOS, use background capabilities only for a user-facing purpose that fits Apple's rules. Background fetch and task APIs are scheduled by the system, so record the actual capture time and expose missed intervals. Don't promise “every minute” collection unless the app is actively running in a permitted mode.

On Android, WorkManager is a better fit for deferrable persistence than a permanently running timer. A foreground service may support an ongoing, user-visible operation, but it adds notification, lifecycle, and policy responsibilities. Battery Optimization can automatically sleep apps, and an app may request an exemption through a no-sleep list during installation or upgrade, as described in Broadcom's Android battery optimization documentation. That exemption should be a deliberate user choice, not a hidden requirement.

Permission design is part of the product

Explain why collection is needed before requesting access to notifications, location, or other capabilities. Battery status itself may not require the same sensitive permissions as location, but your surrounding diagnostics can easily cross that boundary.

Security reporting has warned that battery-status information can be surprisingly detailed and, in some contexts, can help identify or track users in this Guardian coverage of battery privacy. Keep the data model narrow. Avoid collecting location, network identifiers, or device fingerprints unless the feature requires them, and give users a clear retention and deletion path.

Privacy boundary: A battery monitor should explain exactly what it records, when it records it, and whether the data leaves the device.

Testing and Exporting Your Production App

Test the app on physical iOS and Android devices, not only simulators. Verify charging transitions, unplugged use, low or unavailable readings, app foreground and background transitions, device restart behavior, interrupted permissions, and long gaps between observations. Compare your display with the relevant system battery view, but label differences as estimation or attribution limitations rather than “correcting” your data.

Exercise the dashboard across small and large screens, dark mode, accessibility text sizes, empty history, corrupted local records, and a full storage cleanup path. On Android, test manufacturer-specific battery optimization behavior and confirm that the app still communicates clearly when scheduled work is delayed. Use the mobile application testing guide to structure functional, device, and regression coverage before release.

Export the generated React Native code, review native configuration manually, and add logging around permission state, collection time, source, and failures. A production battery usage app should make uncertainty visible. It earns trust by showing what it observed, what it estimated, and what the operating system prevented it from collecting.

RapidNative lets you turn a battery dashboard concept into a shareable React Native prototype, iterate on screens with your team, and export clean code for native battery integrations and testing. Visit RapidNative to start shaping the monitoring workflow before committing to the full implementation.