Constantly empty battery ...

Hello, everybody.

I have a problem with a constantly drained battery on my V8 Lang.

If the car has been standing for less than 1 1⁄2 weeks, the capacity of the battery is no longer sufficient for a start.
The battery (105Ah) is brand new and the alternator has also been completely cleaned (light oil contamination) and measured; it delivers enough "juice".
There must therefore be a constant consumer. According to the Audi workshop, the measured resting current only delivers a slightly higher value. This can't be responsible for the empty battery in this rather short time. The retrofitted Blaupunkt-Navi was also checked for correct connection – nothing was found here either!
Was kann also diesen erhöhten Verbrauch verursachen?
I've heard of defective ZV pressure pumps under the back bench before! Can such a defect have this cause? How can I test whether the ZV pump is functional or defective? ZV and alarm actually work perfectly – only the IR-FB is currently failing your Dinest! Is it possible to test the rest current even in the case of a closed vehicle and an active anti-theft system? I think that the Audi workshop measured the rest current in the case of a parked but unlocked car?

Do you have any other ideas about which consumers can exist? I am grateful for every idea ...