Well Pete, the battery is 9 months old. It has stayed with the + pole disconnected for about a month, the time I was working on the bike.
An bad connection would be a comforting scenario. I will check and clean all connections and sockets and see what happens...
Don't want to add confusion to the conversation BUT, the day before I was getting service light on dashboard. Connected to Guzzidiag I got ECU faults P0115, P0110, P0120, all of them "too high" and finally P0505 "no signal". Like most of the sensors where gone.
The next morning no service light and faults gone... Go figure