Alternators are just like car alternators, they are meant to maintain your battery, not charge it, it is especially bad on motorcycles. Pull the batter and charge it for a few hours, then take it to your local parts store and have them test it.
-2001 Tahoe original 5.3 4x4 only 436k
-Down to 2 three wheelers
-1996 GMC Jimmy
-1985 V65 Magna
-1973 CT70 with 125cc motor