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How to tell if an iPhone battery has already been replaced
Why it matters before you buy or quote
A replaced battery is not automatically a problem — a good genuine cell fitted properly is fine. What matters is knowing, because an aftermarket cell changes what you can promise the customer, and because a battery swapped by someone careless often comes with other damage.
Signal 1 — the phone's own service history
Recent iOS versions record parts history and can display "Unknown Part" or a battery service message. That message is the loudest signal, but it is also the one a seller is most likely to have worked around, so treat its absence as no evidence at all.
Signal 2 — the serial and manufacture date
Every cell carries its own serial and a manufacture date. Two checks matter:
- Was the cell built after the phone? A cell manufactured a year after the handset was sold did not ship inside it.
- Does the manufacturer match what Apple used for that model in that period? Cells come from a small set of suppliers; an unexpected one is worth a closer look.
Signal 3 — gauge records that do not match a fresh battery
A genuinely new cell has a short history: few cycles, a high minimum voltage, low internal resistance, no thermal events. A cell presented as new that carries a deep-discharge record or a raised resistance curve is a used cell, wherever it came from.
What we do about it: PhoneVitals reads all three families of signal and states a verdict with the raw values printed beside it, so the conclusion is auditable rather than a claim your customer has to take on faith.
What to tell the customer
Say what you can prove and no more. "The battery in this phone was manufactured after the handset and its cycle history does not match a new cell" is defensible. "This is a fake battery" usually is not — and a printed report that shows the evidence protects you either way.
Read it from the phone instead of guessing
PhoneVitals pulls every number in this article off the device itself over USB — the gauge records, the panic logs, the pairing checks — and prints them in a report your customer can verify by QR code. The first scan on your computer is free.
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