If you’ve heard the term “alternator” before, you probably know that it’s an essential part of your cars. But what exactly does an alternator do? Simply put, your alternator keeps your car battery charged so you can turn on your car and use electronic accessories like your headlights and radio.
If you are having alternator problems, you may find that your car will not start or stay on for more than a few minutes. Before that happens, however, you’ll likely encounter one or more of these signs of a bad alternator.
How Do You Know if a Car Alternator is Bad?
It can be difficult to tell whether your car has a bad alternator or a bad battery. If you jumpstart your car but it dies immediately after, you most likely have a problem with your alternator. Some warning signs of a failing alternator include:
- Trouble starting your car
- Frequent stalling
- Whining or screeching noise after the vehicle starts
- Dim or overly bright lights
- The smell of burning rubber or wires
- Dead battery
- Battery dashboard warning light is on
If you have noticed any of the warning signs that your alternator is failing, let’s discuss in detali one by one.
7 Symptoms Of Bad Alternator
#1. Trouble Starting.
As previously mentioned, trouble starting your engine might mean that your alternator is failing to charge the battery. This means that when you turn the key in the ignition, all you’ll hear is a clicking sound instead of the purr of your engine.
#2. Frequent Stalling.
A bad alternator almost always results in a car that won’t start. But before things get that far, you may encounter a number of other issues. A faulty or dying alternator may only work intermittently. As a result, the alternator may not have what it takes to keep your battery fully charged—even with the engine running.
As a result, your car may stall at unusual times. The immediate cause of such a stall is often the fuel injectors, which require power to do their job. If a faulty alternator isn’t keeping your battery constantly charged, the injectors may not fire and your engine will stall.
#3. Whining or screeching noise after the vehicle starts.
Cars make a ton of odd sounds — some are harmless while others can indicate serious mechanical problems. If you ever hear growling or whining noises coming from under the hood, you could have alternator problems, which should be checked out by a professional ASAP.
This growling or whining sound happens when the belt that turns the alternator’s pulley becomes misaligned or rubs against the side of the pulley. You may also hear this sound if the bearings that spin the rotor shaft are going bad.
Related Posts: How Much Does It Cost To Replace An Alternator?
#4. Dim or overly bright lights.
The failing alternator symptom most drivers recognize is dim or flickering lights. This is obvious when headlights are on at night, but also noticeable in dash lights and the center dome light. If the lights brighten as RPMs pick up, that’s even more of a sure sign.
#5. Smell Of Burning Rubber Or Wires.
A foul smell from b burning rubber or wiring could indicate that parts of your alternator are starting to wear out. Because the alternator drive belt is under constant tension and friction—and because it’s close to the hot engine—it can wear out over time and give off an unpleasant burnt rubber smell.
Similarly, if your alternator is overloaded or has frayed or damaged wires, you may smell a burning odor that is comparable to an electrical fire. An overloaded alternator tries to force too much current through its wires, causing them to heat up unsafely. Damaged wires also create resistance to the flow of electricity, causing the wires to heat up and give off a foul odor.
When you start noticing certain issues, it’s time for an alternator replacement. You can go to your local auto shop to get this work done. But you should be prepared for a hefty bill.
#6. Dead Battery.
Sometimes a dead battery is just a dead battery — it’s reached the end of its life after a few years of use — or maybe you accidentally left the headlights on all night. Other times, however, a dead battery could be a sign that your alternator is malfunctioning.
A bad alternator won’t sufficiently charge the battery while the engine is running, causing the charge to deplete faster than usual. One way to test whether the issue is battery- or alternator-related is to jumpstart the car.
If you jumpstart your car and it stays running, your battery may need replacing soon. However, if you jumpstart the car and it dies again shortly after, it might mean your alternator isn’t getting enough power to the battery.
Related Posts: How To Test an Alternator with A Multimeter?
#7. ALT Or Battery Warning Light Turns On.
It’s never a good idea to ignore vehicle warning lights, even though some car owners do. Whether it’s a low oil indicator or a service engine soon light, it’s important to address these needs as soon as possible.
Many cars will show a light shape like a battery on the dashboard display or close to the speedometer. While this can sometimes indicate a battery problem, the car’s computer is telling you that the battery is not fully charged, which can also indicate alternator trouble.
Learn more about why the battery light may be on.
With some vehicles, the warning light for the alternator may be an ALT indicator. When the voltage begins to decrease, different accessories will be affected. For example, if you are using your windshield wipers and radio, power from the alternator may not be sufficient to get the headlights on too, as the alternator is already working too hard to power the other systems.
How To Diagnose A Failing Alternator?
If you have a “Check Engine” light on, connect a code reader to the diagnostic port. If you find code P0562, you most likely have a faulty alternator (note that codes can vary by vehicle make/model/year). Get it checked out before it fails altogether.
If you suspect a bad alternator but don’t have a warning light, open the hood and check the condition of the belt. If it looks glassy and slightly burned, that’s an indication it’s slipping. The belt is too loose so it slips on the pulleys instead of riding along them.
The metal-to-rubber friction heats the belt and wears it out quickly. Adjust the tensioner so the belt is just right (too tight can also damage an alternator’s bearings) or replace the serpentine belt as it is one of the cheapest auto parts you can buy. It should be a quick and easy fix.
If everything looks good under the hood, grab your multimeter and test your alternator to the norm. If any of the voltages are below the recommendation, this is a strong case for a new alternator. Also, if you check all of your wiring for corrosion or a loose connection, you may find that you need new alternator connectors, rectifier sets, or brush sets.
FAQs.
A bad alternator won’t sufficiently charge the battery while the engine is running, causing the charge to deplete faster than usual. One way to test whether the issue is battery- or alternator-related is to jumpstart the car. If you jumpstart your car and it stays running, your battery may need replacing soon.
A damaged or worn-out alternator pulley can produce many issues, including unusual noises, such as rattling, squeaking, or chirping.
If your alternator fails when you’re far from home, you can typically drive up to 200 miles on battery power alone. That’s assuming your battery is in good shape and fully charged. Of course, it’s best to get the alternator repaired or replaced as soon as you can.
If you have a “Check Engine” light on, connect a code reader to the diagnostic port. If you find code P0562, you very likely have a failing alternator (note that codes may vary by vehicle make/model/year). Get it checked out before it fails entirely.
An effective method to determine whether it’s your battery or alternator that’s gone bad is to connect jumper cables from a running vehicle’s battery to yours. After a few moments, try starting your vehicle. Once it’s started, remove the jumper cables — if your engine stalls, your alternator has probably gone bad.
