2085 AV HAIG
NAPA Auto Parts NAPA Montréal
2085 AV HAIG
(514) 351-4210
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Alternators and Starters 

Part Types


Alternator's problems occur more often in winter due to the cold weather making it harder for the battery to produce power.

Canadian winters can be harsh and temperatures can go really low, to avoid being stuck with a car that does not start it is important to understand how the alternator and the starter of your car, truck, or SUV work and how to recognize if one of their components is having a problem before it is too late.

The electrical system of a car consists of a battery to generate power, a starter to start the car, and an alternator to maintain the charge on the car battery and power the electrical system when the engine is running. All of these components are crucial and together they provide electrical power to your vehicle.

Important components in the starter motor:

      • Solenoids Plungers
      • Starter Armature
      • Actuating Arm
      • Starter Brush
      • Drive

Important components in the alternator:

      • Pulley
      • Housing
      • Rotor
      • Stator
      • Voltage regulator
      • Rectifier or diodes

Other important components:

      • Connectors
      • Belt
      • Control Relay
      • Crank

If one of those components is giving you problems, visit your closest NAPA AUTOPRO Service Center to get your vehicle checked and fix the problem to make sure your car is ready for winter.


An alternator, also called a generator, works together with the car battery and the car starter. The battery produces power and rotates the starter, which makes the serpentine belt turn from the driveshaft by spinning the alternator. The alternator's rotor consists of a series of magnets that alternate to produce alternating current (AC). Then with the use of the rectifier, also called diodes, converts the AC into direct current (DC).

The function of the alternator is to help recharge the battery and supply power to electrical components when the engine is working. The voltage regulator regulates the electrical current that flows to avoid battery overcharge or does not get drained.

A car starter motor is a main component of the car ignition system. If you are not driving an electric car, without a starter a car engine cannot start running.

The starter motor in your car is a crucial part of the ignition of your car. Inside the starter motor is an electromagnet that is engaged when you turn the ignition switch. A gear is pushed forward which combines with the flywheel or flexplate attached to the crankshaft, which turns over and, there you go! Your engine should start.


What are signs and symptoms of a bad starter?

      • Your engine won't crank
      • You hear loud clicking or grinding noise
      • There are lights in the dashboard but nothing else is happening
      • The starting circuit stays on after starting the engine.

A good way to see if your starter has a problem is by bench testing it. It's a relatively easy test to do. You can either do it yourself at home or visit your closet garage to help you out.

A starter goes bad either because of poor maintenance or normal wear and tear. Some of the parts to check when your starter is going bad:

      • Loose cables
      • Dirty/corroded connection
      • Battery corrosion
      • Check the solenoid and starter relay
      • Overrunning clutch
      • Shaft bushing

If one of those parts is worn out you will need to change it. You can find them all at your closest Napa Auto Parts.


What are signs of a bad alternator?

Usually an alternator does not need too much maintenance unless they are damaged. The average alternator lasts between 7 to 10 years.

What are the symptoms of a worn alternator?

      • Battery needs constant boost
      • Dim lights on the dashboard
      • Trouble starting your vehicle
      • Electrical accessories are not moving at full speed.

To test if your alternator is bad you will need to perform a test with either a voltmeter or a multimeter. If you use a multimeter you will need to set it at DC Volts to measure the voltage of your alternator and to make sure it's working properly. An alternator voltage needs to be between 13.5 and 14.5 anything above or under is an indicator that the alternator is failing. If the alternator passes the voltage test, you can then test the battery. A battery voltage when your car is running needs to be in between 13.7 and 14.7. Anything under is an indication of a dead battery.

How to test an alternator:

      • You will need a multimeter
      • When the car is running the alternator is charging your battery
      • checking your battery
      • starting your vehicle

Quick test to know if it is the alternator that is dead or the battery if your car is dead.

You will need jumper cables, a battery or a vehicle and your vehicle.

Uses the jumper cables to boost your car

  1. Boost your car using jumper cables.
  2. If the vehicle dies right after: alternator needs attention.
  3. If the vehicle continues to run: battery needs attention.


If your starter does not work you won't be able to drive your car. Fortunately, buying a starter is not very expensive. The price for a starter varies depending on the model chosen and whether it is a new or remanufactured part: it can vary between $ 50 and $ 400.

Cost of Replacement Alternator

The cost of an alternator also varies depending on the type and model you buy plus the labor cost to replace it. Like the starters, the price for the alternator varies depending on the model and whether it's new or remanufactured. It can vary from about $100 to over $500.

NAPA offers a complete range of alternator and starter selection. Visit our online store or visit one of our NAPA Auto Parts stores.

It is highly recommended to find a garage that can replace or repair your alternator and car starter near you. Asking the help of a professional will ensure that you get the best parts and service for your car.