Guide · Battery health
How to check iPhone battery health
What the built-in Battery Health screen reports, what it leaves out, and how to tell when a battery is due for replacement.
Every iPhone battery ages. Charge cycles wear the cell a little, until a phone that once lasted a full day is hunting for an outlet by mid-afternoon. iOS ships with a built-in readout for exactly this — but it is a summary, and it leaves out more than most people expect.
This guide covers what Settings actually reports, what third-party tools can and cannot add on iOS, and how to decide whether a battery is still fit for service.
What iOS reports in Battery Health
Open Settings > Battery > Battery Health (labeled Battery Health & Charging on current iOS). Two readings matter. Maximum Capacity is the battery's current charge capacity as a percentage of its capacity when new — a battery at 86% holds roughly 86% of the charge it held from the factory.
Peak Performance Capability is the status line underneath. When the battery can support normal peak power, iOS says so plainly. If it cannot and the phone shuts down unexpectedly, iOS applies performance management — limiting maximum performance to prevent further shutdowns. You can turn management off, at the cost of risking another shutdown. If the battery was serviced with a part iOS cannot verify as genuine, the screen says so instead of reporting capacity.
- Maximum Capacity — charge capacity relative to new; it declines gradually with cycles, heat, and age.
- Peak Performance Capability — normal, or performance management applied after an unexpected shutdown.
- Service messages — iOS recommends service when the battery is significantly degraded, or shows a verification notice for parts it cannot confirm as genuine.
What the Battery Health screen leaves out
The built-in screen is a verdict, not a chart. It does not show cycle count, charge rate, voltage, or how capacity declined over time, and it offers no history or export — so you cannot compare a device with its own past state, or document a battery before a trade-in or repair handoff.
The deeper numbers exist, but Apple keeps most of them inside system diagnostics. iOS does not expose cycle count or detailed battery telemetry to ordinary apps; where the data is available at all, it surfaces through the system's analytics and diagnostics logs. That constraint applies to every app on the App Store — none can read a figure the OS withholds.
What a diagnostics app can add
Third-party tools cannot bypass iOS, but they add two things. They monitor what the OS does expose in real time — battery level, charging state, thermal conditions — instead of a single frozen verdict. And where Apple exposes battery data through diagnostics logs, they help you import and read it.
In Lirum Device Info 2, three tools carry that work:
- Battery — a live monitor for level and charging state, alongside CPU, memory, storage, and network activity.
- Thermals — thermal state monitoring, since sustained heat is one of the fastest ways to wear a battery.
- Battery diagnostics import (beta) — bring in battery diagnostics data where the OS exposes it.
When to replace an iPhone battery
Apple designs current iPhone batteries to retain up to 80% of original capacity after about 1,000 complete charge cycles; older models were rated for 500. A battery is due for service when any of these hold true:
One caveat: with a battery iOS cannot verify, capacity readings may be unavailable regardless of actual condition. Judge it by runtime and shutdowns instead.
- Maximum Capacity has dropped below 80%, or iOS displays a service recommendation.
- The phone shuts down unexpectedly, or iOS reports that performance management has been applied.
- Runtime has fallen to the point that the phone needs a charge partway through a normal day.
- The battery is visibly swollen or the phone is hot while idle — stop using it and get it serviced.
Questions & answers
Battery health FAQ
Short answers to the questions that come up most often about iPhone battery health.
What is a good Maximum Capacity percentage?
A new battery reads 100%. Anything above 90% on a phone less than a year old is normal, and 80–90% is typical after two or three years. Below 80%, or once iOS shows a service recommendation, the battery has reached the threshold Apple itself treats as worn.
Why does my iPhone say it cannot verify the battery?
That message appears when the battery was replaced with a part iOS cannot confirm as a genuine Apple battery. The phone keeps working, but iOS stops displaying health information for that part. Judge it by runtime and shutdowns instead of the missing percentage.
Can a third-party app show my iPhone's cycle count?
Not directly. iOS does not expose cycle count to apps; the figure appears only in the system's analytics and diagnostics data. Lirum's Battery diagnostics import (beta) exists for this reason — it works with the battery data the OS exposes rather than around it.
Is it bad to leave my iPhone charging overnight?
Largely, no. Optimized Battery Charging learns your routine and holds the charge at 80% until just before you usually unplug, and newer iPhones offer an explicit charge limit. Sustained heat does more damage than plug time.
Does performance management mean the battery is unsafe?
No. It means the battery could no longer deliver peak power and the phone shut down unexpectedly, so iOS reduced maximum performance to keep it running. You can turn management off, but an unexpected shutdown may recur until the battery is replaced.