Voltage Regulator and/or Ballast fails

Other possible culprits... bad battery and/or jump starting, or simply bad battery cables.
Years ago a friend had a Nova that repeatedly tossed its charging system, alternator, voltage regulator, or both.
At 1st glance I noticed loose wound electric tape at the end where ground cable lug attached to block. A slight tug and it came right apart. One new cable and another regulator is all it needed. I went ahead and installed the later delco alternator with regulator inside. No more problems. And check that the ground strap from firewall to engine block is securely in place.