How many volts is an alternator supposed to put out on a 91 suburban?
14 to 14.5 volts. Same on all alternators Depending on the load and ambient temperature, the voltage should be between 13.0 and 15.1 volts. Most vehicles with good charging systems will measure between 13.8 and 14.8 volts on a warm day, depending on the battery type that the charging system was designed for. Below 13 volts have the alternator tested.