No need to disengage the shaft on an alternator from the pulley. Easier to just remove the voltage from the field coil.dealership checked out my car's passenger handle and said all was fine. Did talk to me about battery saving feature and that the computer systems of the car do drain the car slowly. He took one look at the fact that my car is just about 1 year old with 3677 miles and said that I should hook up a battery charger with auto float mode to it. He said that our car has the ability to stop the alternator from charging the battery and spin freely/ disengage a clutch as another fuel saving method. As long as the car has enough juice to run the car, the alternator is disengaged. When it gets low, it will reengage and charge the battery again. He did say that because of this , it is not uncommon for the battery to fail sooner.
moral of the story, drive your car more often or take measures to keep the battery above 12 volts.