Signs of Bad Alternators

Have you ever noticed that your car battery drains quickly when using accessories like your headlights or turning on the radio? That’s because your alternator isn’t keeping your battery charged. 

The AC from your alternator helps keep your battery charged so you can normally drive and operate lights, windshield wipers, radio, and other electrical accessories without the risk of draining your battery. 

In other words, when it comes to your vehicle’s power system, the alternator is the main player — it not only provides electricity but also controls the flow of current from a car battery to the rest of a vehicle’s components. 

You should always keep an eye on your alternator from time to time. However, it can be hard to detect abnormalities with your alternators. Luckily, there are some signs you can observe and know whether your alternator is good or going bad. 

Fortunately, this article will break down the most common signs that may indicate the malfunctioning of the alternator. Let’s dive in.

Dead Battery

One of the surest signs that your alternator is bad is if your car’s battery is dead. Whether you try to start the engine and turn on the headlights or attempt to listen to the radio, your battery simply isn’t going to have enough juice for whatever you’re trying to do. 

The alternator’s job is to recharge your battery and keep it at an optimal level of charge. If your voltmeter reads a charge level below 11.4 volts on most vehicles, your alternator is not working normally and needs to be replaced. 

Suppose a faulty alternator is not causing the problem. In that case, other causes could be related to the electrical system, such as bad fuses, a faulty connection in the wiring harness, or even dirty or corroded battery terminals that can prevent electricity from flowing freely. 

You should have any of these problems checked by a professional immediately as they can lead to more expensive and extensive issues with your vehicle down the road if left unaddressed.

Dim or Overly Bright Lights

When your alternator fails, there’s a good chance that your vehicle’s lights are going to be impacted directly. Inconsistent voltage provides you with dim or overly bright lights, as well as flickering and altered brightness levels.


Growling or Whining Noises

Growling or whining noises from underneath your hood could indicate a range of problems. At first, it might sound like someone is just playing with the engine’s gears to let you know they’re there. 

It’s uncommon to hear growling or whining when accelerating fast or hard because the shifting of gears can mean the alternator inside your car isn’t working right and needs replacement.

The smell of Burning Rubber or Wires

A burnt rubber smell and cracked wiring insulation are definite signs of a problem, not only in the alternator but could indicate a short-circuit somewhere else in the electrical system. 

It’s impossible to trace the source of an alternator’s burning rubber odor unless you open it up and re-solder any cracked electrical wires.

Bottom Line

Recognizing signs of bad alternators can save you time and money, but importantly, it saves lives. It is easy to determine whether an alternator needs replacement with time and observation. 

As the old saying goes, an ounce of prevention is worth a pound of cure. A bad alternator can damage the battery, power supply and allow excessive strain on the charging system, which could cause other vital components to burn out.