What the notice says
On an iPhone running iOS 10.2.1 or later, this notice might appear in Settings > Battery: “Your iPhone battery may need to be serviced.”
Why the notice appears
Using diagnostics in iOS, we've detected that the battery in your iPhone may need to be replaced. When a battery gets closer to the end of its lifespan, the amount of charge and the ability to provide power reduces. As a result, a battery may need to be charged more and more frequently and your iPhone might experience unexpected shutdowns.
This isn’t a safety issue, it’s just to let you know that your battery may need to be replaced. You can continue to use your iPhone until you have your battery checked.
There are various factors that can affect the performance and lifespan of your device’s battery, including number of charge cycles, age of your battery, and exposure to extreme heat or cold. Learn more about maximizing battery life and lifespan.
All rechargeable batteries have a limited number of charge cycles and might eventually need to be serviced. Apple’s one-year warranty, AppleCare+, and consumer law include service coverage for a defective battery.If your battery doesn't have service coverage, Apple offers a battery replacement service for a fee.
* Some counterfeit and third-party batteries may not be designed properly and could result in safety issues. To ensure you receive a genuine Apple battery, we recommend visiting an Apple Store or Apple Authorized Service Provider.