We’re sure you’ve heard of an alternator before, but do you know what it does? An alternator helps convert mechanical energy to electrical energy to recharge your vehicle's battery and provide power to other electrical components while the engine runs. The battery cannot maintain a full charge without the alternator, and your vehicle may not start.

You see, the battery and alternator go together like a lock and key— they need each other to work! That’s why it can be tricky to determine whether you have a bad alternator or bad battery, especially if you’re dealing with startup failure. Luckily, there are a few distinctive signs that could indicate a failing alternator.

Signs of a Failing Alternator

Whenever you get behind the wheel, keep an eye out for these possible symptoms of a bad alternator:

Dead Battery

Wait, wouldn’t a dead battery mean it’s a battery issue? It certainly can, but it may also point to an alternator issue. A malfunctioning alternator won’t adequately power the battery while your engine is running, causing the charge to deplete over time.

So, is it the battery or the alternator? Jump-starting your car is a good place to start. If you jump-start your vehicle and it continues running, it’s likely a battery-related issue. However, if you jump-start your vehicle and it dies shortly after, it may mean your alternator isn’t delivering enough power to the battery.

Battery Warning Light

A battery warning light illuminated on your dashboard could indicate a possible battery issue but can also mean you have an alternator problem. If an alternator issue triggers your battery light, the voltage might fall below or exceed the car’s voltage limit. Depending on the electrical load, the warning light might flicker on and off as the system voltage fluctuates. If you see the light illuminate on your dashboard, take your vehicle to a professional for diagnosis and service.

Strange Noises

Growling, squealing, and whining are all normal noises your cat makes, not your vehicle. If you hear a growling or whining sound under the hood, the alternator bearings could be worn down. If it’s a squealing noise, you may need to inspect the belt that drives the alternator’s pulley to see if it’s loose or misaligned.

Headlight Problems

As an alternator begins to fail, it provides inconsistent power to your electrical components, including your headlights. You don’t want dim, flickering, or overly bright headlights while driving at night. If you experience this, the alternator may be delivering sporadic voltage to your headlights.

Stalled Engine

If your engine frequently stalls while driving (and then requires a jump-start), your alternator may have an issue. It might be a sign that your alternator is not sending enough power to your ignition or fuel injection systems to keep the engine running. Take your vehicle to a professional to help you get charged up and back on the road in no time.

Trouble Starting Your Car

Click, click, click. Is that all you hear when you turn your key? If so, your alternator is likely not delivering enough electricity to recharge your battery, preventing your vehicle from starting. You may want to have the trained technicians diagnose the issue.

Problems with Vehicle Accessories

Is your stereo cutting off right before the best part of the song? Or are your windows taking forever to roll down when you're at the drive-thru? If you notice your electrical accessories aren’t working properly, your alternator might not be supplying enough power to them.

Many modern vehicles utilize electronic systems that prioritize where to cut off power if the alternator is not supplying enough electricity. That way, if you’re driving with a bad alternator, it’ll shut off nonessential accessories before your engine stalls.

Odd Smells

The smell of a light roast in your cup holder on the way to work is normal. The scent of burning rubber or an electrical fire? Eh, not so much. If you notice these troubling odors, they may be coming from your alternator. Since the alternator’s belt is under constant tension and friction, it can wear out over time, emitting a burning rubber smell. Additionally, if your alternator is overworked or has damaged wires, it could release a scent like an electrical fire.

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