The essential alternator

The alternator powers your vehicle’s electrical system and keeps the battery charged. Without a functioning alternator, the battery would deplete and your vehicle would stop working. Alternators also work as crucial starters for vehicles equipped with start and stop systems.

Signs of a faulty alternator

  • Battery warning light on dashboard stays lit after starting car
  • Car is difficult to start: battery isn’t charging properly
  • Not enough power for electrical accessories like the stereo, the heater fan or your onboard computer

The certified technicians at NAPA AUTOPRO have the expertise to test your charging system, including the battery, diagnose belt problems or replace the alternator.


If you use additional electrical devices in your car, such as computers, tablets and DVD players, or if you regularly tow a trailer with a battery that recharges as you drive, you can have it upgraded to a more heavy-duty alternator.

Your alternator should be inspected and the belt should be replaced regularly as specified by the manufacturer. Your NAPA AUTOPRO technician will test and install an alternator that meets your manufacturer’s specifications.

Online Resource Centre

How it works.
How to prevent it from breaking.
Who can fix it.