Hi Steffen,
While you can't completely disable the start/stop function, you can adjust its behavior, for example, to "Memory." In this mode, the control unit remembers the last setting. This works on my A4 and on our Golf 7. There are several entries on this topic here.
Battery management has its own peculiarities. For example, in the Golf 7, after starting the engine, the battery continues to be drained by various electrical components for several minutes. Most likely, this is part of the testing cycle (it's about extracting performance from the battery, not the motor).
The generator is only stressed when it's under a significant load. Now I have to teach my co-pilot to immediately turn on the seat heaters, fan, air conditioning, lights, and rear window so that the battery charges quickly...

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Things get interesting when it comes to auxiliary heaters, especially if they were added later. If it's not installed correctly into the vehicle's electrical system, it can drain the battery, especially on short trips.
hg
Herbert.