How to Check Battery Health in iOS 12

Apple’s iOS 12 operating system provides built-in diagnostic utilities designed to monitor battery wear, optimize power management, and identify apps causing excessive drain. This guide explains how to access the native Battery Health feature in iOS 12, interpret critical metrics like Maximum Capacity and Peak Performance Capability, and utilize advanced diagnostics to determine the physical condition of your iPhone's battery.

Built-in Battery Health Feature

The primary diagnostic tool in iOS 12 is located directly within the system settings. To access it, go to Settings > Battery > Battery Health.

This screen provides two key diagnostic metrics:

  • Maximum Capacity: Displays the battery’s current capacity relative to when it was brand new. New batteries start at 100%, while normal degradation typically lowers this percentage over time. Apple considers any capacity below 80% to be degraded and eligible for replacement.
  • Peak Performance Capability: Indicates whether the battery can still support peak processor demands. If an unexpected shutdown occurs due to a chemically aged battery, iOS 12 enables performance management (throttling) to prevent further crashes. This section informs you if performance management is active and provides an option to disable it manually.
  • Important Battery Message: If the battery has degraded significantly or if an unrecognized replacement was installed, a diagnostic alert appears at the top of the screen advising you to service the battery.

Battery Usage and Activity Diagnostics

For diagnosing software-related drain rather than physical hardware degradation, iOS 12 includes a detailed activity dashboard.

Navigate to Settings > Battery to access:

  • Battery Level and Activity Graphs: Interactive charts showing battery levels, screen-on time, and screen-off time over the last 24 hours or the last 10 days.
  • Battery Usage by App: A ranked breakdown of apps by energy consumption. Tapping "Show Activity" reveals the exact hours and minutes an app was active on screen or running in the background.

iOS Analytics Logs (Cycle Count)

iOS 12 records comprehensive hardware telemetry, including the battery cycle count, in raw system logs:

  1. Go to Settings > Privacy > Analytics > Analytics Data.
  2. Scroll down to find logs named log-aggregated-[date].
  3. Open the most recent log, copy the text into a notes app, and search for battery.cycle_count.
  4. The integer following this key indicates the total number of full charge cycles the battery has completed.

External and Support Diagnostics

If you require advanced diagnostics beyond what iOS 12 displays natively:

  • Apple Support App: Initiating a support session allows Apple technicians to run a remote diagnostic test on your device to verify the overall hardware status of the battery and power management chips.
  • Desktop Software: Connecting your iOS 12 device via USB to a computer running tools like coconutBattery (macOS) or iMazing (macOS/Windows) reads the device's internal power management bus, revealing real-time temperature, current charge in milliampere-hours (mAh), design capacity, and cycle counts.