Abstract: A method for controlling a powertrain system includes monitoring a state-of-charge of the energy storage device and determining a first set of electric power limits and a second set of electric power limits based on the state-of-charge of the energy storage device. The method further includes providing a power range for opportunity charging and discharging of the energy storage device based on the first set of electric power limits. The method further includes providing a power range for controlling output power of the energy storage device based on the second set of electric power limits.