How to tell if your battery, alternator, or starter is having a problem

If your car doesn’t start, is it the battery, the alternator, or the starter that is to blame? Because an automobile’s systems are so integrated, figuring out which component is causing your problem can be difficult. In this blog post, we’ll discuss how each of these components works, what can go wrong, and how to tell the difference.

Your vehicle’s battery

Without a battery, your vehicle wouldn’t work. Whereas the engine turns combustion into power to move the vehicle, your battery handles all electrical components, including the starter to actually start your engine.

Signs your battery is malfunctioning:

  • Your engine cranks, but the car won’t start.
  • There is blue foam on the battery, a sign of corrosion.
  • The battery is misshapen.

Your vehicle’s alternator

The alternator keeps the battery charged. It gets its name from its core operation: spinning a field coil that has alternating (N) and (S) poles.

Most driving occurs in city stop-and-go traffic. This prevents the battery from staying fully charged. The alternator fills in this gap by adjusting to the battery’s needs.

Signs you have a failing alternator:

  • The battery warning light is on.
  • You smell burning rubber.
  • All headlights are either dim or overly bright.
  • The vehicle stalls often or has trouble starting.
  • You hear a growling or squealing noise.

Your vehicle’s starter

You’ve probably seen old film footage or historical movies where someone crouches in front of a car and manually turns a hand crank rod to start the engine. Today’s starters perform the same function, but they’re certainly easier to use and not as dangerous.

The starter in your vehicle is a high-torque electric starting motor. When you insert your key into the ignition or press the starter button, you’re completing an electrical circuit that results in your engine starting. Once your engine has started, you turn back your key or release the button to break that circuit.

Signs your starter is damaged:

  • Not only does your car not start, but your engine won’t crank.
  • Smoke is coming from your car.
  • Lights turn on, but your engine won’t start.
  • You hear a clicking, grinding, or whirring sound when you start the vehicle.

So, battery, alternator, or starter?

Because these systems are so tightly intertwined, the answer isn’t always easy to find. Let’s look at the steps you can take to deduce what the problem is.

Start with the battery

Because a battery only lasts three to five years, it’s most likely the problem.

First, open the hood and check that your battery cables appear to be in working order. If everything looks fine, disconnect the cables for safety. Instructions are here.

Next, remove any corrosion from your battery. If the battery has caps, first clean the surface beneath them with a scraper to ensure a tight seal. (You can lift the caps gently with a flat screwdriver.) Then mix baking soda and water, wet a cloth, and scrub on and around the terminals until clean.

Once everything has thoroughly dried, safely reconnect the cables.

Last, test your battery with a multimeter. If your battery can’t hold a 12.4 V charge, replace it. You can find a new battery guaranteed to fit your vehicle by visiting our website and entering your vehicle information in the top left-hand corner. You’ll find more information about types of batteries here.

If your battery can hold a charge, try to recharge it. You’ll find a full list of instructions on how to safely recharge a car battery here.

Check the alternator

Only an experienced DIYer should inspect the alternator on their own. If you’re new to this task, take your vehicle to your nearest NAPA AUTOPRO service centre.

To read more on how to test your alternator yourself, read this handy guide.

Inspect the starter

If both your battery and alternator pass their tests, then the starter may be the problem.

Many of the problems that can cause a starter to break down start in its electrical systems. We’ll cover a few ways to test the starter, but if you’re inexperienced, you may need to have your vehicle towed.

Find the starter in the engine bay. Your user’s manual will show you where. Using a hard object, gently tap the starter. This might tap the electrical components back into place, but it’s most likely a temporary fix. Take advantage of the temporarily repaired starter to drive the vehicle to a service centre.

If your car is in “park” when you start it, try moving it to “neutral” to see if it starts. If it starts, then the issue may be a technical glitch. Take your vehicle to a service centre in this situation, too.

Jump starting a vehicle can also be a temporary fix that will give you time to drive to a service centre. We have a guide on how to safely jump start your vehicle here.

When in doubt…

Unlike an oil change or surface damage to your vehicle, like cracked windshield wiper blades, your battery, alternator, and starter are part of a complex electrical system. If you have any doubts at all about inspecting these components, please visit a local auto shop for your safety. You can find your nearest NAPA AUTOPRO service centre here, and one of our technicians will be more than happy to help.

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