About iPad and iPhone charge-management feature
iPadOS and iOS include a charge-management feature to maintain battery health when an iPad or iPhone XS, iPhone XS Max, iPhone XR, or later is connected to power for prolonged periods of time.
iPad and iPhone are portable devices that are designed to be used all day on a single battery charge. There are times, however, when an iPad or iPhone is connected to power for prolonged periods of time, such as when it's used in kiosks, point-of-sale systems, or stored in charging carts. iPad and iPhone use rechargeable lithium-ion batteries, which are designed to be charged and then discharged over their lifespan. When they remain at full charge for prolonged periods of time, battery health can be affected.
iPad with iOS 11.3 or later and iPhone XS, iPhone XS Max, iPhone XR, or later with iOS 12 or later include a charge-management feature to help maintain battery health. This feature monitors these devices for use in these charging situations and, as required, temporarily reduces the capacity of the battery. The battery indicator in the status bar will display the remaining charge percentage based on this adjusted capacity. The battery capacity will revert to the nonadjusted level when iPad or iPhone is no longer connected to power for prolonged periods and as conditions and battery health allow.
iPad Pro (M4) models and iPad Air (M2) models with iPadOS 17.4 or later provide battery usage information in the Settings app. If an iPad has been connected to power for prolonged periods and the charge-management feature has been active, the Maximum Capacity as shown in Settings > Battery > Battery Health might be temporarily unavailable. When the iPad is no longer connected to power for extended periods and is allowed to complete a number of full charge cycles, the Maximum Capacity field will be able to reflect an accurate value.
