According to Apple the batteries in the iPhone 15 series have a longer lifespan than previously stated. Following updates to the Battery Health setting in iOS 17.4, Apple reveals that the iPhone 15 can maintain 80% of its original capacity after 1000 complete charge cycles, up from the initial 500 cycles.
Testing involved charging and discharging the battery 1000 times under typical usage scenarios. This improvement is attributed to ongoing enhancements in battery components and power management systems. Note that this change applies solely to the iPhone 15 series, while older models retain the previous 80% capacity at 500 cycles.
However, Apple is currently exploring similar updates for older iPhone models too.