The alternator produces AC voltage, the rectifier in the alternator turns it to DC volts that the vehicle uses. If the rectifier was bad it would send AC voltage into the battery and vehicle systems. If you get 13-15v DC output from the alternator, it works properly.If I understand you correctly, if the rectifier in the alternator is leaking ac then it won’t be supplying enough voltage to charge the battery?
I don't mean to add any more confusion to your original problem.