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Can a Bad Battery Harm Your Starter or Alternator?

Power - by Bryan Veldboom - updated on 6/16/2021

Hood of a car open

Today we'll be talking about how your car's battery, starter and alternator work together to turn over your engine, power your electrical system and recharge your battery so that it can continue working. We'll also tackle a few of your most common questions regarding engine failure and help you determine which of these three components is responsible.

How Does a Battery and Starter Work to Turn Over Your Engine?

In order for your engine to start, it needs to be turned at a fast enough speed to suck fuel and air into the engine's cylinders and compress it. When you engage your car's engine, a signal is sent to your vehicle's battery causing a chemical reaction, which creates electrical energy. The shaft of your vehicle's starter contains a gear wheel which connects with a large gear ring around the rim of the engine's flywheel. Your starter uses electrical power from the battery to turn the engine, delivering fuel into the engine cylinder and compressing it.

What Does an Alternator Do?

While your car's battery is responsible for starting your car when it's turned off, it's the alternator that provides the direct current (DC) power needed to run your vehicle's electronics while you're driving. This includes things like headlights, power steering, power windows, windshield wipers, dashboard instruments and radios. Your alternator is also responsible for recharging your battery while you drive. It does this by converting the mechanical energy created by driving into electrical energy.

Can a Bad Battery Cause Electrical Problems?

Yes, if your battery is underperforming it can cause systems within the vehicle to malfunction. A bad battery can also result in air conditioners, stereos and other applications not receiving enough power to function properly.

Does a Bad Battery Affect Your Starter or Alternator?

A bad battery won't usually harm your starter or alternator, however, since both of those components get their voltage directly from the battery, if the battery is underperforming, both the alternator's and starter's performance will be affected as well.

How Do You Tell If It's Your Starter or Your Battery?

Here are a few common signs that your starter may be failing. Keep in mind that many of the issues can also be caused by a bad battery. A good rule of thumb is to jump start your car. If you have a bad battery, jump starting should start the engine. If that doesn't work, it's a good sign that the starter is at fault.

  • Difficulty starting your engine
  • Noises when turning over your engine, including clicking, whirring or grinding

What are Some Signs of a Bad Alternator?

Here are some warning signs that your alternator may not be working properly. Keep in mind though, that many of these issues can also be caused by a bad battery. As mentioned above, if you're unsure which one is at fault, trying jump starting the vehicle. If your car stays running afterward, it's probably a battery issue. If your car dies shortly after jump starting it, it's probably an alternator issue.

  • Dim or extremely bright lights
  • Slow or malfunctioning accessories
  • The dashboard battery warning light goes on

Batteries Plus Will Test Your Battery, Starter and Alternator for Free

If you're experiencing any of the issues mentioned above, there's an easy way to get answers. Just bring your vehicle to any Batteries Plus location and have it tested, free of charge. We'll test your battery's Cold Cranking Amps and voltage, as well as your car's starter and alternator to help you determine the problem.

If it turns out to be battery-related, our experts can help you find the best replacement option for your made and model. Plus, we offer expert installation on most vehicles at most of our locations. Find your nearest Batteries Plus store, or shop our selection of car and truck batteries online. If you need a battery installed, you can cut down on your wait time by scheduling an arrival time that's convenient for you. Have another auto issue? Visit our automotive center for headlight bulbs, wiper blades, key fob replacement service and more.

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