Apple confirms iPhone 15 series batteries have longer lifespan

Apple has confirmed that the iPhone 15 series offers tangible improvements in battery life. All four iPhone 15 models can retain up to 80% of their original capacity after 1,000 charges under ideal conditions while previous models were rated at 500 charges for the same capacity. Apple has released updated battery life metrics on a dedicated iPhone battery support page.
Apple also told 9to5 Mac that it used a specific charging test that involved charging and discharging the battery 1,000 times under specific conditions that would simulate real-world usage.
The development is due to “constant updates to battery components and power management systems over the years,” and Cupertino is also investigating older iPhone models to see how their batteries stack up.
There are multiple asterisks here because battery wear can vary greatly between users depending on many factors, including regular use and charging patterns.