I have 1982 Fleetwood Brougham and the voltage ranges from 12.5 all the way up to 17 volts! i took off the alternator and had it checked at the place i bought it and they said everything was fine. so i reinstalled it and it did work at the proper range (12.6-14 volts) and then after i drove away the voltage began fluctuating again. also, the battery has clean connections, it's a new optima red-top and the grounds to the body and engine are good. if anyone has any ideas of what may cause this problem other than a faulty internal voltage regulator on the alternator please enlighten me!!!