Battery Or Alternator: How To Tell Which Is The Problem?

Every vehicle needs a power source. Now, we aren’t talking about electric cars in this blog posts, but your typical everyday gas or diesel vehicle. In a traditional set up a car works like this for supplying power:

You turn the key which starts the chain reaction of all the functions needed to start your car, run, or the accessories to work. The battery is then used to perform these necessary functions. If you leave the car in an accessory position, or on, and not fully start the vehicle all the power applied to operate the accessories will draw power from the battery. After a period, your vehicle’s battery will wear down, and not allow the car to start. However, if your car is turned on and the engine is running the part called an alternator will recharge the battery, thereby you have constant power on demand.

But how can you determine whether or not you have a bad alternator or a bad battery? Is there a way to find out without replacing one or the other or both? Are there symptoms you can check to diagnose the problem? BMW auto repair at Ryan G. Motorworks can give you a correct diagnosis if you are nervous about messing with these critical components. We will explore some of the symptoms and even go over a way to check whether or not you can place the blame on the alternator or the battery.

Symptoms of a Bad Alternator

The symptoms of a bad alternator can be confused with a dead battery problem. More often than not it takes testing to find out if it is, in fact, a failing alternator. There are five signs that an alternator is an issue and they include:

  • Dimming headlights
  • Slow operating windows
  • Electrical failures- including power door locks
  • Difficulty in starting your vehicle
  • ALT light is illuminated on the dash

Symptoms of a Bad Battery

A dying battery and a dead one will experience similar issues. However, if the battery is completely gone, nothing will turn on with the vehicle. You can insert the key, no chime will play alerting you to a door being ajar, and you won’t have anything illuminated on the dash. Perhaps the worst part of having a completely dead battery is the car won’t even try to start. If you are able to jumpstart your vehicle and it remains running after disconnecting the cables, it’s a good indication that the battery is at fault. A failing alternator can cause a dead battery, so it may not be time to replace the battery itself, without first determining which is the problem.


If your vehicle starts, chances are it isn’t your battery that is the problem. Allowing your car to run and then disconnecting the positive cable from the battery terminal. If your car is still running, the alternator is fine. This means you will need to replace the battery.

Searching for German auto repair near me, you will find that Ryan GMW can help you to replace a battery or alternator quickly, and get you back on the road. They can also help you to identify which is your problem if you have difficulty or would rather a professional handle electrical components.

Is It A Starter Or Battery Problem?

You are having a problem starting your car; it is slow cranking, or when you turn the key to start it the lights dim, or you hear absolutely nothing or you hear a clicking.

These things can indicate either a starter or battery problem. However, these symptoms can also indicate other problems.

If you are unsure which it is, you can bring your vehicle to an Auburn BMW Repair shop that can help you by testing your battery and starter.

Signs Your Battery Is Getting Weak

Your battery can become weak over time. Here are a few signs that your battery is becoming weak;

  • Your car cranks slower
  • You hear clicking when you turn your key or press the start button
  • The car started yesterday but won’t start or was extremely slow starting the next day
  • Battery terminals are corroded
  • The battery case looks bloated
  • Your battery is older than 3 years old

If you notice any of those problems, a BMW Repair Rocklin shop can help you.

How To Maintain Your Battery?

There are some things you can do to help maintain your battery and keep it working well.

  • Check the battery post/connections for corrosion and clean it off. Mix 2 tablespoons of baking soda with a cup of warm water, stir it up. Pour the mixture over the terminals and use a wire brush to remove the corrosion.
  • Make sure the connections are tight.
  • Check the fluid inside the battery if your battery has lids to do that.
  • Visually inspect the outside for leaks which can cause corrosion, bulging of the battery, or other signs that your battery does not look right.

Signs Your Starter Is Going Bad

As with other parts on your vehicle over time your starter will wear out; what are the signs that your start is going bad?

  • When you start your car, you hear any of the following sounds; buzzing, whirring, grinding, or clicking
  • Your lights dim when you start your car

If You Think Your Starter Is Going Bad, Here Are Some Things You Can Do

If you are having trouble starting your car and think it may be your starter;

  • Make sure all the connections are tight; that includes bolts that mount it.
  • Make sure the wires are not frayed or showing through the coating.

Understanding The Ignition System Of Your Vehicle

There are several parts to your ignition system;

  • The battery provides electrical power to the other components
  • The electrical current is sent through the alternator
  • The starter when the key is turned brings the electrical current from the battery through the alternator to start the vehicle.

Getting Help For Your Starter Or Battery

If you have been experiencing issues when starting your car and are unsure of what it is or how to fix it; bring your vehicle into BMW Repair and we will test the battery and starter for you.