How to tell whether your iPhone battery needs replacing

Open Settings → Battery → Battery Health. Apple prints a maximum capacity percentage. It is not a marketing badge. It is a comparison against the cell when it was new.

At 100–90% most people notice nothing. Between 89% and 80% you start to see the last hour of the day disappear. At 79% and below iOS may show a peak-performance warning. That is the line we use on the bench: if you are already rationing brightness, book the swap. Waiting until the phone dies at 20% in the cold only makes the shutdowns more dramatic.

Numbers lie when the phone has had a cheap cell already. If Battery Health looks fine but the back is lifting, believe the bulge. A swollen cell is a same-day job — not because we like the drama, but because it can crack the display from the inside.

Unexpected shutdowns in winter are another tell. Lithium cells sag in the cold. A tired one sags far enough that the phone cuts power to protect the board. Plugging in “fixes” it for ten minutes. That is not charging magic. It is voltage recovering above the cutoff.

Bring the phone in. A replacement on Market Street is typically 30 minutes. Aftermarket cells restore everyday life. Newer iPhones may show a “unable to verify genuine Apple battery” message after a non-Apple cell. The phone still charges. We say that before the adhesive comes off.

If you want the Apple-branded cell, ask. When we can get one, it costs more and we write that on the job sheet. There is no third secret grade called OEM that is “the same as Apple.” If a shop uses that word, ask whose factory and what the warranty covers.