An agricultural baler , comprising: a main bale chamber ; a plunger reciprocally movable within the main bale chamber through a compression stroke and a return stroke, said plunger having a duty cycle with a maximum power requirement , a minimum power requirement , and an average power requirement over the duty cycle; a flywheel ; a gearbox coupled with the plunger for reciprocally moving the plunger within the main bale chamber , the gearbox being driven by the flywheel which in turn is connected via a drive shaft with a power take-off coupler ; and a driveline having an input end couplable with a power take-off (PTO) of a traction unit, and an output end coupled with the gearbox ; characterized in that the agricultural baler further comprises an auxiliary power system (APS) coupled with the driveline , said APS being configured for receiving power from the driveline , storing the power, and transmitting the stored power back to the driveline to offset the duty cycle of the plunger and thereby establish a substantially constant power requirement at the driveline , wherein the APS includes a power generation device configured for receiving power from the driveline and generating power when an actual power requirement during the duty cycle is approximately below the average power requirement , a power storage device coupled with and configured for storing power from the power generation device , and a power feedback device configured for transmitting the stored power back to the driveline when an actual power requirement during the duty cycle is above the approximately average power requirement . a main bale chamber ; a plunger reciprocally movable within the main bale chamber through a compression stroke and a return stroke, said plunger having a duty cycle with a maximum power requirement , a minimum power requirement , and an average power requirement over the duty cycle; a flywheel ; a gearbox coupled with the plunger for reciprocally moving the plunger within the main bale chamber , the gearbox being driven by the flywheel which in turn is connected via a drive shaft with a power take-off coupler ; and a driveline having an input end couplable with a power take-off (PTO) of a traction unit, and an output end coupled with the gearbox ; characterized in that the agricultural baler further comprises an auxiliary power system (APS) coupled with the driveline , said APS being configured for receiving power from the driveline , storing the power, and transmitting the stored power back to the driveline to offset the duty cycle of the plunger and thereby establish a substantially constant power requirement at the driveline , wherein the APS includes a power generation device configured for receiving power from the driveline and generating power when an actual power requirement during the duty cycle is approximately below the average power requirement , a power storage device coupled with and configured for storing power from the power generation device , and a power feedback device configured for transmitting the stored power back to the driveline when an actual power requirement during the duty cycle is above the approximately average power requirement . <EOS>