It does kind of sound like that you are having a wiring/contact soldering issue with the instrument pod.
Hmm... Sorry if it's a stupid question, but wouldn't then the issue also occur while driving (eg, the clock would be off while driving)? ?
 
Hmm... Sorry if it's a stupid question, but wouldn't then the issue also occur while driving (eg, the clock would be off while driving)? ?
Not necessary, it is only, I think, the initial loss of charging after starting that is causing the battery voltage to drop down too far, or the voltage that the car's systems "see" gets dropped down too far at this time.
 
This has just started happening on my 1.9 fsi Leon. Battery light flashing although charging at 14.4v when running and the clock resetting every time the ignition goes off. It must be a sensor fault somewhere. Later models tend to have the battery health sensor on the battery earth lead but not been able to find it on mine yet. Strange indeed.