An agricultural baler includes a main bale chamber, a plunger reciprocally movable within the main bale chamber through a compression cycle, a flywheel associated with the movement of the plunger, and a driveline associated with the flywheel and couplable with a power take-off of a traction unit. The baler has an auxiliary power system coupled with the driveline. The auxiliary power system includes a power indicator providing an output signal representing a parameter associated with power usage during the compression cycle of the plunger, a power device for at least one of receiving power from and transferring power to the driveline, and an electrical processing circuit coupled with the power indicator and the power device. The electrical processing circuit is operable for receiving the output signal(s) and controlling operation of the power device, dependent upon the output signal(s).
