iPad is a portable device that is designed to be used all-day on a single battery charge. There are times, however, when iPad is connected to power for prolonged periods of time, such as when it is used in kiosks, point of sale systems, or stored in charging carts.
iPad uses 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.
iOS 11.3 includes a charge management feature to help maintain battery health, which monitors iPad for use in these situations and, as required, reduces the maximum charge level. The battery indicator will display the charge based on the adjusted maximum battery level. The maximum charge level will revert back to the previous level when iPad is no longer connected to power for prolonged periods and as conditions and battery health allow.