An aircraft hybrid electrical system includes an electric power generating system in signal communication with a thermal combustion engine, a secondary power system in signal communication with the electric power generating system, and a battery in signal communication with the electric power generating system and the secondary power system. The aircraft hybrid electrical system further comprises a system controller in signal communication with the electric power generating system, secondary power system, and the battery. The system controller is configured to monitor a charge capacity of the battery and selectively operate in a current charge mode and a voltage charge mode to charge the battery. The system controller invokes the current charge mode in response to detecting the charge capacity falls below a charge capacity threshold, and invokes the voltage charge mode in response to detecting the charge capacity reaches a target value.