A self-propelled lawn mower has an on-board battery, an electric blade motor for rotating a grass cutting blade, said blade motor being operationally connected to the battery, an electric drive motor for propelling the lawn mower along a grass surface to be cut, said drive motor being operationally connected to the battery, and a control unit for controlling at least the operation of the electric drive motor and of the blade motor. There is provided a speed monitor for monitoring the speed of the drive motor. This monitor is also connected to the control unit. There is also provided a motion speed selector for selecting a predetermined speed for the drive motor. The motion speed selector is also connected to the control unit. A total energy monitor is provided for monitoring the total energy consumption of the battery. The total energy consumption is the electrical energy consumed by the drive motor plus the electrical energy consumed by the blade motor. The total energy monitor is also operationally connected to the control unit. The user can select a predetermined maximum energy value by means of a maximum energy selector, which is operationally connected to the control unit. The control unit is designed to keep the speed of the lawn mower on the predetermined speed value, independently of the pushing force of the user, and to reduce the total energy as soon as the total energy exceeds the predetermined maximum energy value. The lawn mower affords a comfortable operation for the user, and the battery is protected from overload.
