Abstract: A workload dependent load-sharing mechanism in a multi-battery system. The mechanism is an energy management system that operates in three modes—energy saving mode, balancer mode, and turbo mode. The energy saving mode is a normal mode where the multiple batteries provide power to their own set of loads with least resistive dissipation. In balancing mode, the batteries are connected through switches operating in active mode so that the current shared is inversely proportion to the corresponding battery state-of-charge. In turbo mode, both batteries are connected in parallel through switches (e.g., on-switches) to provide maximum power to a processor or load. A controller optimizes the sequence and charging rate for a hybrid battery to maximize both the charging current and charging speed of the battery, while enabling longer battery life. The hybrid battery comprises a fast charging battery and a high-energy density battery.