Monitoring system comprising a door closer

A monitoring system comprising:

• a door closer for closing a door (200),
• with a housing and an output shaft supported therein, designed for fastening a lever arrangement,
• with a mechanical energy storage device in the housing, which drives the output shaft to rotate in a closing direction of rotation, wherein the energy storage device is preferably a spring, wherein the output shaft can be rotated into a first angle range, which can be used to open and close the door, and into a second angle range wherein the second angle range is not occupied by the output shaft if the door closer is properly installed on the door and in operation, and a limit between the first angle range and the second angle range represents a closed position of the output shaft,
• with a sensor unit for detecting an actual angle of rotation dependent on the angle of rotation of the output shaft,
• and an evaluation unit,
• wherein the evaluation unit is designed to generate a message when the actual angle of rotation is in the second angle range,
• wherein the door closer comprises a module with at least one battery, the second door closer is properly installed on the door and in operation
• wherein the module comprises a module circuit board and the module is fastened by means of the module circuit board.