Check all your connectors. My 900 had the same problem, I replaced the rectifiers stator, everything, still had the problem. Went through all my connectors, cleaned them real good and haven't had to charge her since.
Not guaranteeing this is the problem, but its a good, cheap place to start and really should be dome anyways. Good luck!
It's only illegal if you get caught.
If at first you don't succeed, use more lighter fluid
95% of Harley Davidsons ever made are still on the road... The other 5% made it home.
New Baltimore, Va '82 CB900c, 1980 CB985F/K 'Mutt"