Symptoms of a Bad Alternator in Your Car

bad alternator symptomsMy car will not start and my neighbor looked at it this morning and thinks I might have a bad alternator.  In your opinion what are the symptoms and signs of a bad alternator and how can I test it myself?



Hello there Dorthy,

Well, if the engine will spin over and over but will not start, you have another issue and it is not related to a battery or alternator problem.  Signs of a bad alternator are pretty simple.

The alternator charges the battery, so if the battery is dead it MIGHT be because of a bad alternator. Of course, a dead battery could be due to a BAD battery, or a loose connection at the battery not allowing the alternator to recharge it.

This is a great video talking about common alternator failures and symptoms

My super simple rule of thumb. If the battery looks old or you know it is at least 3 years old I would replace it. The average life of a car battery is about 3.5 to 4 years. So if you are 3 years old and having a dead battery issue I would just replace it and see what happens.

Testing the old battery at this point would be a waste of my time.  I would need to charge it overnight first, then I would need to “load test” the battery to see if it can hold any loads and charges that the alternator will place on it. Again, if your battery is older than 3 years, I would not go through the hassle.

If the new battery goes dead after you have been driving for a while, then yes the alternator could be bad or you still have a battery connection/cable issue that is not allowing the alternator to recharge the battery.

If possible, I would replace the battery then have your alternator out put checked at your mechanic. This is the proper way, but if you are on a budget, grab your jumper cables and hit the roads closest to your house. You will probably get some kind of battery warning light on your dashboard if the alternator is not keeping up with the demand of the battery.

As a side note. A car that has a weak or worn out battery can cause the alternator to work much harder than it should, causing premature alternator failure. Another reason to replace the battery every 3 1/2-4 years. Which is much cheaper than a new alternator and a tow truck bill.






6 Comments on "Symptoms of a Bad Alternator in Your Car"

Trackback | Comments RSS Feed

  1. cruz F Lucero says:

    My 2009 4 cylinder Altima suddenly died on freeway and will not crank over, let alone start. I tried jumping it with cables- no luck any suggestions

    • Austin Davis says:

      Install a brand new battery first, make sure all battery terminal connections are clean and tight then check the alternator output to make sure it is recharging the battery properly.

  2. Reggie says:

    I have been through 2 Autozone alternators and my battery light is still on.

    • By Austin Davis says:

      I would ASSUME you do NOT have an alternator problem after all and would triple check the battery cable connections, load test the battery and check all ground connections to the battery and alternator. Also, if you have an external voltage regulator I would check or replace that too.

  3. Jack says:

    I tried to overhaul the alternator myself, don’t bother with it. Took a while, had a hard time finding the parts and you can buy a rebuilt unit so cheap these days it was not worth my time.

  4. John says:

    I am an alternator rebuilder (one of the few left) and it is a little cheaper coming to my shop and letting me overhaul your existing alternator than buying a new one from the part store, but you have to know what you are doing.

Got Something to Say?