Like rjsfishin said. Never check the alternator by removing the cable. Slap whoever told you that. Is the belt tight or even on the engine? Is the fusible link OK? Check all the terminals and connectors before replacing anything. Remove the NEGATIVE cable from the battery when working on any cables or connectors at the alternator. DONT let the wrench arch near the battery or you risk having a bomb go off in your face. The battery produces hydrogen gas when charging or discharging. If its charging it should read between 13.7 and 14.2 volts when running.