MK5 GTI Alarm on Battery disconnect

[ab11]

Hello

I'm about to garage my 2008 GTI over winter and to avoid battery drain and depletion (like last year) I'm trying to leave the battery disconnected but car locked.
When I remove the negative terminal the alarm sounds, I gave it a minute before I reconnected the neg terminal as neighbours curtains were twitching. Pressing the buttons on the remote had absolutely no effect.

Does anyone know the correct procedure to disconnect the battery without this happening? There is nothing in the handbook of course.

[the-photographer]

It might be the battery in the alarm module, these can fail and randomly sound the alarm, its around £250 to replace.

On the MK6 the alarm battery is only charged when the engine is running