Nissan Repair: Help with alternator, nissan maxima, carbon brushes

Question
Hello Von,

I have a 1996 Nissan Maxima
I was told that my alternator is dead but the car starts fine. Is it possible for a car to start just on battery? I just had the serpentine and drive belts changed and the mechanic told me I also needed a new alternator. Please help me out.

Answer
Josephine,

The car starts with the battery and the alternator is for powering the electrical system when the car is running and also keeping the battery charged for starting and running things when the engine is off.  I would ask the mechanic why the alternator needs replacement.  Now, it could be that the bearings are going out and when he was changing the belt he noticed the bearings were noisy or the brushes are going out.  The electrical connection in the alternator is provided through carbon brushes and when they wear out or get close things can really get messed up inside.  So, if either are the case I would change the alternator.  If the alternator is not making noise when the pulley is turned and it puts out 14.2 volts it is fine.  But, with the age of the car it is quite possible the mechanic is trying to keep you from getting stranded in the near future.