According to numerous reports on Reddit, Apple’s iOS would use a kind of low-performance mode, with a CPU downclock, to avoid sudden restarts of devices with worn batteries.
The Reddit TeckFire user posted the Geekbench results before and after replacing the battery on a used iPhone 6s. Before replacing the battery, the device achieved a single-core score of 1466 and 2512 in multi-core. After replacing it, Geekbench instead indicated a single-core score of 2526 and 4456 in multi-core. The rate of battery wear was about 20%.
According to other reports, this “problem” would have occurred on some iPhone 7 and would be linked to a news of several months ago concerning, in fact, the sudden shutdown of some iPhone 6 and iPhone 6s. A problem due to an excessive energy absorption of the A8 and A9 chips on the iPhone whose batteries showed a high level of wear.
Among other things, iOS now warns users when the battery has been recharged for 500 cycles and recommends replacing it. The message appears in Settings> Battery:
Apple may, therefore, have found a “solution” to the problem, with a CPU downclock. The Cupertino company, at the moment, has not issued any statement on the matter.