Not charging correctly

Hi, a while ago I felt a bang under my bum which felt like the battery exploding or jumping in it's slot (it was around that area) since then it's not charging correctly, starts off ok sitting around 13.5/14 but the. After a couple of minutes drops to 12/12.5 and stays there, does that sound like the alternator rather than the R/R or something more serious. 1999, fix

Pull the battery and take a look. Carefull see if it will take a charge and go get it tested. Then review the thread below. Also look for wires/connectors burnt - sounded like something shorted. 

If you remove the seat and then the rear cowl, you can see all the possible offenders. I'd take a look at the alternator-RR connector with the three yellow wires, these get dirty, corrode, then the increased resistance leads to heat and ultimately will melt the connector so the different phases can short out and lead to problems elsewhere. If that's OK then move to the RR and check the voltage output. As you probably already know, failing RR's are an inherent weak spot on a VFR. Your symptoms of good charging voltage initially, then dropping to 12/12.5 does sound like a RR fault, but don't discount a failing battery.