Troubleshooting Your Car’s Battery And Alternator

Batteries and alternators are critical parts of your car's electrical system. You car won't run without both of them working correctly. Here is how to troubleshoot electrical system problems involving these components.

How These Components Work Together

When your engine is not running, your battery provides all of the power you need to run the electrical components in the car, such as the lights and radio. It also is needed to start the engine. When the engine is running, the alternator also provides electricity to the engine while charging the battery. Without the battery, you can't start your car. Without the alternator, your car will eventually stop running when the battery becomes exhausted. Knowing this helps you troubleshoot these electrical problems.

Battery Problems

Like any other rechargeable battery, your car battery will eventually stop taking a charge, causing it to fail. For most batteries, this can take several years to happen. As your battery gets to the end of its life, you may experience the following symptoms:

  • if you turn off the engine with the lights still on, they become dimmer
  • your engine will turn over more slowly each time you try to start it until the battery is completely dead

Determine if the problem is an old battery or an alternator that is failing to charge the battery. You can test this by doing the following:

  1. Start the car.
  2. Open the engine hood and find the battery.
  3. With a socket wrench, remove the positive battery cable from the battery.

If the car continues to run smoothly, then the alternator is likely fine since it is providing power to keep the car running without the battery. Take your car to a service center and have them replace the battery for you. If the battery cables are corroded, have them cleaned or replaced to make sure you have a good connection to the battery.

Alternator Problems

Alternator problems can initially look like a battery problem. Some of the symptoms of a bad alternator include:

  • the electrical system warning light on your dashboard flashes or stays on after starting the engine
  • a relatively new battery begins to show signs of wearing out sooner than expected
  • the engine begins running rough after driving for several minutes

These signs indicate that the alternator is not charging the battery and doesn't generate enough electricity for the spark plugs to keep the engine running smoothly.

To test this, repeat the engine test from above by taking the positive battery cable off of the battery while the engine is running. If the engine runs rough as soon as you remove the cable, the alternator is likely failing.

You'll need to take your car to a service center to replace the alternator. A complete repair can mean replacing the following:

  • alternator and wiring to the battery
  • engine belt that drives the alternator
  • belt tensioner to make sure the belt is always against the pulleys

Battery and alternator problems can escalate quickly, resulting in a car that won't run. If you experience any of these electrical system problems, get your car into a service center immediately and avoid an expensive tow bill. Contact a company like AERS Auto Electric & Refrigeration Ltd for more information.