5 Signs of a Bad Alternator

visibly frustrated person leaning against the hood of a car with their hand covering their faceWhat Does an Alternator Do?

An alternator works in tandem with a car battery to charge the vehicle’s electrical systems. But if you’ve ever found yourself in a position where you’re wondering, “Does a bad alternator make noise?” or “What does a bad alternator sound like?” it’s a telltale sign that it might be time to get it replaced. Check out the five main signs of a bad alternator that impacts cars of all makes and model types.

1: Flickering Headlights

It Still Runs states that dimming headlights is one of the first signs that your alternator is starting to malfunction. If you notice that as you increase or decrease the speed of your engine that your headlights will grow brighter and dimmer, this is a red flag. An alternator that is in good working condition will maintain bright headlights no matter what speed you are traveling.

left side of a sedan with the headlight shining brightlyBesides flickering, your headlights may also begin to weaken or grow dim. Lights that are dim across the dashboard are also indications of a problem. Both flickering and dimming are strong indications that your alternator is no longer capable of generating adequate power.

2: Weak or Dead Battery

A battery that seems to be weak or has died may mean your alternator is going bad as well. An alternator can help replenish the battery in your car, but it can’t keep it going indefinitely. This means it’s important to distinguish between a weak battery and a bad alternator.

person retrieving jumper cables from the trunk of an SUVAccording to Nationwide, there are a few different ways to find out if you’ve got a dead battery or an alternator gone bad. Without starting the car, you can check the battery gauge on the dashboard. If it’s still sending out a strong charge, the battery is likely not the problem. It’s important to note that once an alternator goes bad the electrical devices will attempt to draw power from the battery, which in turn could cause the battery to die more quickly.

3: Strange Sounds

An alternator has a lot of moving parts that spin when it’s working correctly. If one of these parts starts to work ineffectively or breaks off, you may hear some unusual sounds. If you’re hearing a grinding sound in your car, this could indicate that the alternator is going bad. The grinding sound may be caused by a worn-out bearing.

Your car can also make a whining sound when the voltage regulator is sending signals to the alternator to charge more than is necessary. If you hear any type of whining or grinding sound that’s a good indication that your alternator needs to be checked.

4: Difficulty Starting Your Car

The alternator could be bad if your car won’t start or it’s turning over several times before finally starting. Of course, a weak or dying battery could be the problem, but if you’ve already eliminated this possibility it’s likely your alternator isn’t working.

detailed view of a car alternatorFirestone Tires reports that if the alternator has failed, a warning light will normally come on. Most vehicles have a specific light that is battery shaped that will come on to signal if there is an issue. Some may even say ALT. Alternators often have outputs between 13 and 15 volts. If it’s not working correctly the voltage can go below or above these levels, which will signal the warning light. In the beginning stages of a problem this light may come on and off sporadically.

5: Electric Failures

Since the alternator is the primary source of electrical power in your car, electrical failures are signs that it is going bad. Electric failures could present themselves in a variety of ways. Your power windows could operate more slowly. Other items that could be affected include power locks, windshield wipers and heated seats.

While these are all signs that your alternator is going bad, to know for sure you’ll need to have it tested. There are home tests that can be conducted but to know for sure what problems are occurring and how to fix them effectively you should have your car tested by a trained mechanic.

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  • From my experience over the years, when an Alternator goes, it usually just goes fast. You will find your battery is not charging. Many time it will just go and you will see the needle on the dashboard will just drop and show it not charging anymore. Always check the belt also, if it is bad or loose it can stop charging to.

    • My alternator went out yesterday dash lights just went dead headlights went dim then my car cut completely off


  • I was driving my 1996 Cadillac Deville yesterday and lost power steering air-conditioning. I got a message on my dashboard that battery had no charge. There’s better I’ve had three batteries replaced and alternator checked over the last year and a half but this is the first time I’ve lost complete control of the car. It was terrifying. Is this my alternator Or some other electrical problem. I’m elderly and don’t have a lot of extra money to spend but this is the only vehicle I have for transportation. Please help. Thanks

    • This is surely alternator problem. You simply need to replace your alternator and save further damages of your car through affecting battery.
      Signs of faulty alternator:
      1) Unusual binning sounds + burning smells + drying coolants … because of faulty alternator—consequently it collapses battery —- and hence the steering getting hard to turn or move — accordingly vehicle fails to drive.
      Prescription: Replace alternator.

  • My alternator went dead on my 2003 Honda Accord without a warning the other day. I smelled a strange smell but didn’t think anything of it, thinking it was the outside smell. Stopped for gas, got back on the highway and my radio started going in and out, then my airbag light came on, my ABS light, Brake light,etc. Then the control panel shut down, my headlights started flickering and my car just shut down completely while driving. I turned on my hazard lights and they started to flicker and dim completely. Such a scary experience because I was on a country road, sitting in the pitch black. But I replaced my alternator and my weak battery with my dad and she’s working like a charm!

    • Get a classic your be safer

  • my truck keeps dying and I’m not leaving anything on to kill the batteries ( I have 2)

    • Hi, Zachary. This is an unusual situation. Perhaps asking professional technician may be the best step. If you have any other questions please contact consumer support at producttechsupport@goldeagle.com

    • You might have a short somewhere. Check to see what the last work you did to your vehicle then go from there.

  • I drive a 2003 Toyota Corolla 160i GLS. took the car to the car wash and had its engine washed. afterwards the electric windows are not opening, wipers don’t work, radio doesn’t play, speedometer doesn’t read. basically everything is of inside and has a unstable Rev.
    all fused are good, didn’t blow

    • did you figure it out? going through that now.

  • my car could not start, immediately we bring in. another battery, it will start and goes of again what is the possible problem, it a look so show battery symbols on the dashboard but it will not start

    • Hi, Wale. In this particular situation, perhaps it would be helpful seeking a second opinion from a different professional technician. If you have any other questions please contact consumer support at producttechsupport@goldeagle.com

  • Nothing was left on to drain my battery it was dead before I went to work so had it jumped off worked just fine all the way to work then I shut it off and tried to crank it ahead and nothing happened it died again it didn’t take 15 mins from house to work is it my battery dead or alternator

    • Hello, we recommend to possibly consult with a professional as this is difficult to diagnose without being there to test the battery/alternator.

  • Two days before, the fan for the heater went. I was driving along. I noticed that the car didn’t have as much pickup as usual. Then all of the indicators started to go a bit wild and acted like wind shield wipers. On and off, pause and then again. I pulled over to the side of the road and decided that we had better get out of the vehicle (despite the fact that I had an eighty five year old in the car). It was a good thing that we got out as the fan had burned itself out (maybe days earlier). We replaced the alternator and then still had some problems with the battery.

  • great subject ..

  • I drive a 2009 Toyota Camry and my alternator is going bad. i have already bought a new battery and my battery is starting to die out very quickly. reason Alternator Belt.

  • I have a 2001 sebrs I’m trying to figure out if it could be my battery or alternator when you start the car ever thing seams ok put it in gear and the battery light comes on if I hook jumper cables up to it everything is fine

  • I appreciate the information given in this article regarding the abnormalities in the alternator. The alternator is an important part of the electrical system of the vehicle as it generates the electrical energy required to run different types of electrical appliances used in the car. An alternator should be inspected regularly and any sign which indicates that the alternator has some sort of mechanical abnormalities should not be ignored. Mechanical abnormalities associated with the alternator should be subjected to inspection and needs to be repaired in time to ensure continuous power supply to different types of electrical appliances used in the car. For more assistance about the alternator maintenance, visit https://www.grouponemotorwerks.com/german-auto-electronics-repair/

  • My 2012 Chrysler 200, started losing power and the lighting bolt came on, is that battery or alternator? It shook a little took.

    • Hi, Verlene. Perhaps in this situation it may be best to speak with a professional. If you have any other questions please contact our Consumer Support Team at producttechsupport@goldeagle.com.

    • Lightning bolt on a Chrysler is the throttle body is bad.. You may also get a Chk engine light and it may drive only in one gear and maybe even not reverse.. also has a knock in the engine…

  • One way I always used to determine a bad alternator (at least in the old days) get the engine running and carefully remove the terminal cables from battery. If lights and devices stay on, its good, otherwise the engine may also just shut off or devices will shut off (i.e) radio, lights etc…

    • It’s the weather.

  • I have a 2004 VW Passat. Replaced 4 alternators in last 16 months, 3 of them were in last 90 days! We have replace the battery too. Finally the last altenator we put on last week was NEW Bosch, whereas previous ones were all remanufactured. We thought they were just bad, but now this new one is charging but the current is bad and tests like a faulty voltage regulator. Mechanic has checked all cables, wiring, grounds, everything he could think of. What is causing my altenator to continuously fail over and over? Just bad aftermarket OEM? I even looked up VW.com and they only have remanufactured OEM alternators for my make and model. HELP?!?!?!?! I can’t keep paying 3.5 hours labor every week!

    • Turns out the starter may have now gone out. Could that have been blowing the voltage regulators in each of these alternators?

  • I have a 2005 denali yukon xl & i got some work done last week on Tuesday which was an oil leak , which they had to take out alot of parts to my truck it cost me 650 to fix it I noticed that this week she wont start as of a week became Tuesday & today she still won’t start i tried to get a jump & the cables got very hot when i put them on my truck to see if it was my alternator they got red & very hot not sure whats wrong with my truck please help is it something they could have did prior to me getting it last week when i turn on the defrost it makes this humming noise

  • Hello there. I’m so glad I stumbled into this article. I have an old Toyota Camry and recently my battery seems to drain faster these days. I haven’t taken the car to the auto repair shop yet. A friend also told me tensioner belt could be the problem, is this true? Anyway, At least now I have an idea on where they can start

  • My Honda Accord 2001 had some issues and went to workshop. According to the technician I have replaced gasket, power steering and air filter. After replacing the Power Steering there was some noise specially in the morning first start when turn steering wheel completely. Technician said this is normal and will go out the sound after few days. However it remain the same and again I have visited the workshop to address the noise problem. Now technician said because of the ALTERNATOR that is happening and I must replace it. I am really disappointed because I have already paid more than 1000 USD and again they recommended to replace the alternator. I needed good advice please help me. Is this genuine problems ? My battery working well. What happens if I drive my car in the same situations? I am thinking to replace alternator once it will completely die. Still I am not convinced because of the alternator power steering make noise !!!!!

  • My car has been showing signs of problems since last week whenever I turn the lights on in order to drive in the night, and I think this isn’t a sign of an electrical problem. As you’ve mentioned, it’s been flickering whenever I press the gas pedal, so this could be a sign of a problem with the alternator. I think I’ll take it to an auto repair shop so it can be fixed as soon as possible.

  • Just put a new starter on my car and when I turn it over it still wine what does that mean if I just put a new starter it was doing that with the old starter

    • We’d recommend having your car inspected by a mechanic. We cannot diagnose the issue for you unfortunately.

  • Well I’ve been looking for my problem I don’t really see it on any pages my truck battery started dying while we were driving or something and it’ll be all we bought a new battery sound check the battery so the battery is no good so we got another one from Les Schwab brand new then they said that battery was no good I don’t believe that that could happen I was wondering if there’s other reasons that would destroy a battery that quick and I don’t believe it was put on wrong

  • Thank you for sharing this information. I had my GEN light come on yesterday morning, stayed on during the 14km round trip to drop a worker off. Then in the afternoon the GEN light went off once jeep was started and stayed off during the 18km round trip(i went the long way to charge battery – hoping that that is the problem as its been sitting for long periods since lockdown.) This morning however, GEN light went off, and came on again after 50metres driving and stayed on, Battery gauge was on the edge of the red, and by the time i was halfway home I was praying to GOD that I would make it as jeep started to lose engine power (no ooomph) … lost my headlights as i entered the driveway (long driveway, mutiple cars parked in a tight area.. no headlights was quite nerve wracking.. oh did i mention these morning drop offs’ occur at 5.30am and it is DARK. but, through the grace of GOD I made it home. Now what ? Any suggestions ? I am anticipating a rather hefty mechanic bill 🙁

  • My 2012 Ford Escape has stalled several times this week. I recently just put a new battery in it, but apparently, it stalled out again twice today as I was trying to do doordash. When I turned off my engine and turned it back on, it made a whirring sound and wouldn’t start.

  • Hi, good day. My car is actually working but once I use my wiper, breaks or headlights the battery indicator turns on. I actually asked 2 mechanics regarding it. one says that the alternator is broken and needed to be fixed. The other one said that the alternator is good showing me that the battery’s voltage/wattage is on 13-14. I’m confused if i really need to replace my alternator or not, since it was recently replaced.

  • A bad alternator almost always leads to a dead or drained battery. I learned from Dig My Ride that dead batteries due to broken alternators are one of the most notorious causes behind cars not starting. It’s such a hassle getting stuck in the middle of nowhere because of a dead battery that’s why it’s important to take care of your car’s battery and alternator. Thank you for this!

  • My alternator just produced a whining sound. The battery still being charged but at a high RPM like 2,500. The charge indicator says at 13,1Volts on Aircon at high RPM of 2,500 how long will the alternator last? The bad part is am at the trails am about 90 miles away from home