With the launch of the iPhone 15, Apple introduced an optional setting that limits the maximum battery charge to 80%, claiming this can improve battery life. To explore the effectiveness of this feature, MacRumor conducted a detailed test.
MacRumor author Julia Clover used her iPhone 15 Pro Max with the 80% battery charge limit turned on since September 2023. She followed Apple’s charging recommendations, and after 299 charging cycles, the battery retained 94% capacity, meaning the device lost only 6% of its battery health.
Julia charged her phone with a USB Type-C cable 70% of the time and used MagSafe for the remaining 30%. She also compared her findings with other iPhone 15 Pro Max users.
In a comparison, one employee’s battery capacity dropped to 87% with the optimization mode turned off after 327 cycles, while another saw a 90% capacity after 271 cycles. This suggests that Apple’s charging optimization helped Julia preserve an additional 4% of battery life despite a 28-cycle difference.
Comparison graph showing the battery capacity (%) versus charging cycles for the iPhone 15 Pro Max after 12 months. The blue bars represent the battery capacity, and the green line shows the number of charging cycles for each user (Employee 1, Employee 2, and Julia).
While the difference may seem small after one year, it’s possible the 80% charge limit will show more significant benefits after years of use. However, Julia points out that the 80% battery charge sometimes left her without enough power to get through the entire day.