Battery that no longer holds a charge

Apple considers a battery under 80% of maximum capacity (shown in Settings > Battery > Battery Health) to have reached the normal end of its life, and a replacement would bring back the original battery life and performance.

An ageing battery loses its ability to deliver a big burst of current (flash photo, gaming). The iPhone then protects itself and shuts down earlier than the percentage suggests.

The iPhone checks the battery's authenticity through a dedicated chip. A quality battery that isn't officially paired can trigger this purely informational message without stopping the phone from working normally.

It's a classic symptom of a worn battery whose real capacity no longer matches the software's estimate. A replacement brings back a reliable reading and consistent battery life.

Often it comes from using the phone while it charges (gaming, GPS, streaming), which works the processor and battery at the same time. An ageing battery can make the heat worse - worth checking in a diagnosis if it's new.

No, it's a MIUI power-saving software feature, independent of the battery's real condition - it can delay notifications even with a brand-new battery.

Used with the original or a certified charger, fast charging is designed to handle the heat it produces. It's mostly non-certified chargers, with incorrect voltage negotiation, that speed up wear.

Before concluding it's a hardware problem, check the background apps that keep restarting - sometimes seen on models without Google services. If the drain continues after a software check, a battery diagnosis is worth it.

Sudden shutdowns, a visibly swollen back, battery life collapsing within a few weeks, or unusual overheating are the most reliable signs. A quick diagnosis confirms it before any replacement.