Why Your Car Alternator May Be Burning Out (+Solutions)

Replacing a faulty alternator can set you back several hundred dollars depending on the brand and capacity of the alternator fitted.

And so, it is not sustainable to have an alternator burning out every so often – more so, considering that some alternators can last for over 20 years!

So what causes an alternator to burn out and how can you prevent it?

The good news is you may be able to prevent an alternator from burning out.

Read on to find out why the alternator might burn out and what you can do to prevent it from happening.

Note: Do not hesitate to contact a qualified mechanic!

What Causes an Alternator to Burn Out?

While a car alternator can work reliably for several hundreds of thousands of miles, it can burn out too. An alternator can overheat and burn out if:

1. It is Overloaded or overworked. If the alternator works for a prolonged time, it can overheat and burn out.

Many alternators are designed to keep the battery topped up rather than charge a deeply discharged battery and can overheat and burn out when used for the latter.

An alternator may overwork if the battery has:

  • an internal short, or
  • been drained and the alternator is tasked to charge it

What to Do

Use an external car charger to charge a deeply discharged battery instead of using the car alternator.

If the car battery overheats or shows signs of damage, arrange to have it tested at a reputable auto parts store and replace it with another if damaged.

2. The airflow around the alternator is poor. Is the engine compartment unusually hot? Has the car engine overheated recently?

Higher than usual ambient temperatures in the engine bay or restricted airflow around an alternator can also cause an alternator to burn out.

What to Do

Investigate why the engine bay is overheating in the first place. Could it be that there isn’t sufficient coolant in the radiator or the radiator needs servicing?

Whichever the case, arrange to fix it. Contact a qualified mechanic for assistance.

Why your Car Alternator Keeps Burning out (+How to Fix It)

If the car alternator keeps burning out, it may be:

1. That the wire connections between the alternator positive (B+) and the battery positive or the grounding of the alternator is damaged or weak and not providing for sufficient current flow to the battery.

Inspect both the alternator and battery positive and ground connections.

Make sure there’s no corrosion and that the wires are clean and make firm contact. You can also do a voltage drop test.

How to Conduct an Alternator Voltage Ground Test

What you need: Good quality multimeter.

Testing the Negative ground and Positive circuit voltage drops

  • Start the car engine. Set the voltmeter to read voltage. Place the black probe of the multimeter connected to the negative terminal on a known ground connection for the car. Look for a stud on the car’s metal chassis.
  • Next place the red meter probe connected to the positive terminal on the alternator ground connection. The voltage reading should not exceed 0.2V. If higher, confirm that the connections are clean and make firm connections to the respective terminals.

If the voltage drop is still higher than 0.2V even after confirming the cable connections, then there is probably a broken or damaged cable connection that you need to identify and replace.

2. The Car battery is faulty. It may have an internal short that then causes the alternator to overwork and fail.

Use a digital multimeter to get a readout of the battery voltage. A battery with an internal short such as a dead cell usually measures sub 12 V, about 10.4 -10.7 V from 5 cells if one is shorted.

Voltages will be lower if the 2 or more cells have short-circuited.

You may also be interested in this post: Signs that a car battery is shoring

Have the car battery tested by a reputable auto repair shop and replace it if found faulty.

Signs of a Burnout Alternator

When an alternator burns out, it fails with no voltage output and you may likely observe:

  • battery warning light on – signaling a fault with the car’s electrical system
  • an unmistakable burnt wire smell from the burnout stator windings
  • burning smell or smoke from under the hood
  • the id tag – listing the alternator specifications may also be discolored and shrink too when you inspect the alternator closely

Warning: Touching the alternator can cause serious burns and injury.

Do not attempt to touch it unless it’s sufficiently cooled down. Always consult a qualified mechanic.

Closing Thoughts

Replacing an alternator can be costly depending on the type and model of your car. If the car alternator keeps burning out – check for loose alternator and battery wire connections.

Confirm that the alternator has good airflow and that the battery is in good condition too.

These are some of the common reasons why the car alternator may be failing and burning out.

Do not hesitate to contact a qualified mechanic!

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