Had a similar thing recently. Battery would suddenly appear flat, despite bike being used most days. First suspects were battery and reg/rect. Battery was charged on Optimate and seemed fine. Left on draining board, disconnected from bike, and voltage drop over a couple of days was negiligible. Reg/rect charging voltage checked, and fine at 14-14.2V. Reg/rect charging voltage checked
when bike was hot (I've had *that* one before!). Likewise fine. Continued to find severe voltage drop when battery connected to bike.
Disabled/disconnected alarm unit
No more probs! Getting a replacement alarm unit fitted under warranty tomorrow.
Moral; it ain't always the reg/rect. Even on a Ducati.
(Although I believe the later 3-phase ones like mine are better. But not perfect.)
[Edited on 15-10-2004 by moto748]