Method for charging a starter battery and charging device for charging a starter battery

1. A method for charging a starter battery of a vehicle, wherein the vehicle comprises at least one movable opening element and a motor unit coupled to the opening element and operable in a motor-powered drive mode to drive the opening element and in a generator mode to generate an electrical voltage, said method comprising:

detecting the generator mode of the motor unit using the electrical voltage generated by the motor unit,

comparing the generated electrical voltage with a specified voltage value,

establishing an electrical connection from the motor unit to the starter battery to charge the starter battery if the generated electrical voltage is greater than the voltage value,

determining a temperature of the motor unit, and

establishing the electrical connection from the motor unit to the starter battery only if the temperature determined is below a threshold temperature.

2. The method as claimed in claim 1 , wherein the voltage value is a voltage that can be supplied by the starter battery.

3. The method as claimed in one of claim 1 , wherein the establishment of the electrical connection only takes place if the electrical voltage generated in the generator mode is greater than the voltage value by a threshold.

4. The method as claimed in claim 1 , wherein the threshold temperature is a critical temperature of the motor unit.

5. The method as claimed in claim 1 , further comprising:

briefly interrupting the electrical connection after the electrical connection has been established.

6. The method as claimed in claim 5 , wherein the brief interruption of the electrical connection is carried out alternately with the establishment of the electrical connection.

7. The method as claimed in claim 5 , wherein the brief interruption of the electrical connection only occurs if an electrical power generated by the motor unit in the generator mode exceeds a power threshold.

8. The method as claimed in claim 5 , further comprising:

briefly short-circuiting the motor unit after the electrical connection has been established, wherein at least one of the brief interruption of the electrical connection and the brief short-circuiting of the motor unit only occurs if an electrical power generated by the motor unit in the generator mode exceeds a power threshold.

9. The method as claimed in claim 1 , further comprising:

briefly short-circuiting the motor unit after the electrical connection has been established.

10. The method as claimed in claim 9 , wherein the brief short-circuiting of the motor unit is carried out alternately with the establishment of the electrical connection.

11. The method as claimed in claim 9 , wherein the brief short-circuiting of the motor unit only occurs if an electrical power generated by the motor unit in the generator mode exceeds a power threshold.

12. The method as claimed in claim 1 , further comprising:

determining a state of charge of the starter battery,

wherein the step of detecting the generator mode of the motor unit and the step of comparing the generated electrical voltage with a specified voltage value are only performed if the determined state of charge is below a predetermined state of charge threshold.

13. The method as claimed in claim 1 , further comprising:

determining an operator input,

wherein the step of detecting the generator mode of the motor unit and the step of comparing the generated electrical voltage with a specified voltage value are only performed if the operator input matches a predetermined reference input.

14. A charging device for charging a starter battery of a vehicle, comprising:

at least one movable opening element and a motor unit, coupled to the opening element and configured to drive the opening element in a motor-powered drive mode and further configured to generate an electrical voltage in a generator mode, wherein said motor unit is electrically connected to the starter battery by an electrical connection and the charging device comprises:

an electrical switch element, arranged in the electrical connection and having a first switching state configured to establish the electrical connection and a second switching state configured to interrupt the electrical connection, and

a control unit configured to control the switching states of the switch element, wherein the control unit is further configured to carry out a method as claimed in claim 1 .