When should you replace your iPhone battery? In short, the moment your battery drops below 80% of its original capacity. You can find this information in the smartphone settings: tap “Settings” -> “Battery” and “Battery status and charging”. A more understandable (and obvious) sign of the necessary replacement is the frequent discharge or unexpected shutdown of the smartphone.
Apple claims that iPhone batteries are “designed to retain 80% of their original capacity over 500 full charge cycles under normal conditions.”
Source: Ferra

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