How to check if Alternator is Bad? Do you want to know the signs or symptoms that show if the alternator is bad? Then you must keep reading. For you to know the signs showing you may have a bad alternator, you should first understand what an alternator’s function is all about.

How to check if Alternator is Bad

The work of an alternator is to generate an electrical charge to recharge your battery as your vehicle depletes the electrical charge the battery carries. However, without recharging, all the electrical systems inside the car will eventually stop working.

There are lots of reasons why an alternator can fail, but driving in hot weather for long periods of time is the major culprit.

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How to check if Alternator is Bad

Two of the easiest way to determine if your alternator is dying are the battery test and the headlight test. Find out how to perform both battery and headlight tests in the sections beneath.

How to Perform Battery Test

A battery test is easy to perform and you can do that at home. To get started follow this guide;

  • First, open the hood and start the car
  • While the engine is running, remove the negative cable from the battery.
  • If the vehicle stalls or dies, the alternator is likely bad. This happens due the alternator is not generating enough electricity to keep the engine running on its own. But, if the car continues to run, the problem may lie with the battery.

These are the steps to perform the battery test.

How to perform the Headlights Test

The headlight test is also quick and easy and should be done outdoors. This is to ensure that you don’t have a carbon monoxide buildup inside your garage.

So to perform the headlight test, do this;

  • Start your car
  • Then, turn on your headlights.
  • With the vehicle in park, click on the accelerator while a second person observes the headlights.
  • If the headlights flicker, dim or get brighter when the accelerator is pressed down, your alternator may be bad. However, if there’s no change in headlight brightness indicates that your alternator is likely fine.

These are steps to conduct a headlight test.

However, the only way one can be certain about the alternator’s condition is by having it tested by a technician. Most service stations can test an alternator but will charge you for the labor. While many auto parts stores will test alternators, starters, and batteries for free, you will have to remove the alternator to have it tested at an auto parts store.

How to perform Battery Test – How to check if the Alternator is Bad

Here are the common signs of a failing alternator.

Dim or Overly Bright Lights

When an alternator begins to fail, it brings inconsistent voltage to your electronic accessories. Normally, that takes the form of under-or over-performing equipment, just like headlights that are either too dim or extremely bright. Also, you may experience flickering lights or lights that go from bright to dim and vice-versa.

Dead Battery

A bad alternator will not charge the battery well while the engine is running, thereby causing the charge to deplete faster than usual.  You can jumpstart the car to know if the issue is from the battery.

So, if you jumpstart your car and it stays running, your battery may need replacing soon. But, if you jumpstart the car and it dies again shortly after, this might mean your alternator isn’t getting enough power to the battery.

Slow or Malfunctioning Accessories

An alternator that isn’t supplying enough power to your car’s electronics mostly leads to slow or non-working accessories. And if you notice your windows taking longer than usual to roll up or down, or if your seat warmers feel “off”, or even if your speedometer and other instruments start going haywire, you may have an alternator problem.

Trouble Starting or Frequent Stalling

If you turn the key in the ignition, and all you hear is a clicking sound instead of the purr of your engine, it might mean that your alternator is failing.

And if your car is frequently stalling out while driving, it may be a sign that the spark plugs aren’t getting enough power from the alternator to keep the engine running.


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