A power management system has a controller including one or more processors. The controller is configured to monitor electrical power on a power bus of a vehicle. The power bus is electrically connecting a power source to multiple subsystems of the vehicle for powering the subsystems via the electrical power on the power bus. The controller is further configured to determine that the electrical power on the power bus exceeds a designated power generation limit, and, in response, generate a reduction command message for communication to a lowest-priority subsystem of the subsystems. The reduction command message instructs the lowest-priority subsystem to reduce power consumption.