An agricultural baler (10) includes a plunger reciprocally movable within a main bale chamber (26) during a compression stroke and a return stroke, a flywheel (44) associated with the plunger (30), and a driveline (50) associated with the flywheel (44) and couplable with a power take-off (PTO) of a traction unit. The baler is characterized by an APS (52) coupled with the driveline (50) and configured for receiving power from the driveline (50) and storing the power. A PTO indicator (90) provides an output signal indicative of an engagement of the PTO. An electrical processing circuit (62) is coupled with the APS (52) and the PTO indicator (90), and controls operation of the APS (52), dependent on the output signal from the PTO indicator (90).
