Need help!! Alternator charges fine then drops out. Was working last night then quit. let it set for a while and it started charging. Got in it this morning and it wouldnt show a charge all the way to work bout 8 miles or so. Let it set for a while got in it and it was charging again. checked voltage at battery 13.6 and alternator post 13.6. havent checked yet when gauge is showing low voltage. checked all the wires all are tight and clean. could it be the regulator going bad? please help