Finally I've installed the Ctek in my engine compartment (for winter sleep) and connected it with the extender cable.
Additionally I had to install an extender cable from our carport to my car (because I don't have a garage for the winter anymore).

Last time I've checked the Ctek has been short time after the installation.
First it showed a charging time of 4 hours, but then switched to "go" (80 % charged) after 2 minutes.
Hopefully it will switch to care mode when the battery has been completely charged.
Unfortunately I won't be able to check this, because my car is wrapped in two car covers and two blankets ( additionally used a lot of army cord to secure the covers).

I hope that my stupid neighbor won't try to disconnect or cut the cable (yes he's not afraid to trespass our property), because he doesn't like my car.
