First thing to check is the connections for the battery and the reg/rect.
Generally there are three wires comming from the stator (altenator) If you measure the voltage between any pair of the three wires you should get around 70 V AC at 5K RPM. If you get a very low reading on one pair. the stator is history needs to be replaced. If the stator checks ok, wiring is Ok You need a new reg/rect