Might need to recalibrate the regulator or replace regularator nside alternator, not hard. Cheaper than new alternator. Check voltage to battery before starting and recheck after a start. Voltmeter needed. If sitting without startingand voltage 12 v , fine, should be 13v-15v while running, that would mean no charge. Probably will not hurt to do a load check on battery, as once started voltage will drop due to high amps to get starter moving. Might have left something out, but sure more will come.