Might be time for a new battery? I had an old Harley that the starter would not disengage on when the battery was getting marginal, would keep trying to turn over the engine till it completely died. better get a battery tender when you get the new battery also, the jr. model is only about 30 bucks.
Have one of these also, I replaced the battery 1.5 yrs. ago. It didn't do that. But it was an Interstate that went in. Had to special order as it is an oddball and very expensive battery. Save over 40 dollars over the dealership but has worked great since it is on the battery tender.