Alternator Fault Battery Not Charging: 7 Problems & Fixes!

First, the broken serpentine belt of the alternator can prevent charging. Second, damaged ECU and voltage regulator of the alternator can also cause this issue. Battery terminal corrosion and worn-out alternator brushes can hinder the charging too. Last, the alternator might be completely broken.

The alternator works silently to charge the car battery and keep different functions working. A working alternator means a healthy car. The battery will stop charging as soon as the alternator fails.

This is just the tip of the iceberg. Keep scrolling to learn more about alternator faults that stop battery charging.

Key Takeaways

A number of reasons can restrict the alternator from charging the battery of the Audi car.
The solutions and fixing costs vary widely according to the issue of the alternator.
Sometimes the issues can be fixed by DIY. But professional help is a must at other times.

Alternator Fault Battery Not Charging: Quick Solutions

Several issues can cause the issue of the battery not charging just like the muffler rattle of Grand Cherokee. And the solutions to these problems also vary. Go through the following table to know the causes and solutions at a glance.

Cause	Solution	Cost
Damaged Serpentine Belt	Replace The Belt	$90 to $230
Broken Alternator	Changing the Alternator	$200 to $700
Bad Battery	Get A New Battery	$100 to $300
Battery Terminal Corrosion	Clean the Terminals	N/A
Worn Out Alternator Brushes	Clean/Replace The Brushes	N/A
ECU Problem	Fix/Replace The ECU	$500 to $1700(Brand New ECU)
Damaged Voltage Regulator	Change The Regulator	$240 to $380

Only these quick solutions might not be enough to solve the battery not charging problem in your Audi. Since an alternator is a complex machine, you will need more details. So keep reading!

Alternator Fault Battery Not Charging: Detailed Solutions

The battery issue of Audi cars is very sophisticated. So following a detailed guideline is a must.

Damaged Serpentine Belt:

This is the first and most common reason that restricts the battery from charging in Audi cars. A serpentine belt, aka the drive belt, transmits power from the engine to the alternator.

If this belt is broken, it will not be able to rotate the alternator. Thus the battery will not be charged.

Damaged Serpentine Belt — Source: autodoc

Solution:

A cracked or frayed belt must be replaced for the normal functioning of the alternator. Here is a step-by-step guideline for replacing the belt.

Turn off the vehicle and access the alternator at first. The alternator is located towards the front of the engine. Then disconnect the negative terminal of the battery.
Find the tensioner pulley. It is located at one end of the belt. Then use a wrench to rotate this pulley. You can also use a serpentine belt tool instead of the wrench. The tension on the belt will release as a result of this.
Now slide the old serpentine belt from the alternator pulley while rotating the tensioner. Then let go of the tensioner and remove the old belt completely.
Install the new belt onto the pulley. Make sure to follow the vehicle and belt manual while doing this task.
Now use the wrench again to apply tension to the new belt. Recheck the alignment after applying tension.
Once you are done, close the hood of the vehicle.

You can easily replace the serpentine belt by following the above steps. You can also follow this video to make the task easier.

Cost:

The cost of a new serpentine belt varies from $15 to $80. If you take help from a professional, the labor cost will be about $75 to $150.

Broken Alternator:

The battery of your Audi will stop charging if the alternator is damaged or broken.

The alternator goes bad due to various reasons. However, the most common reason is wear and tear due to continuous use. Besides that, a bad or short battery, wiring issues, overuse, etc can also damage the alternator.

Solution:

Fixing the alternator requires experienced hands. So make sure that a professional diagnoses it. Anyway, often the alternator is damaged beyond repair. Then it must be replaced with a new piece.

Cost:

The cost of a new alternator is between $100 to $400. And the labor cost for this task will be about $100 to $300. So get ready to spend about $200 to $700 to replace your old alternator.

Bad Battery:

A battery lasts for 3 to 5 years on average. Then it starts to get weak. And a weak or damaged battery will not hold or take charge. This problem can also happen with new batteries. So it’s very important to verify the health of the battery if it fails to get charged.

Solution:

Damaged batteries can not be repaired or fixed. So a battery replacement is necessary if the battery is completely damaged. Follow the below-given instructions to replace the battery.

Locate the battery of your vehicle at first. It is usually situated in a corner under the bonnet. However, some models store the battery in the car boot.
Remove the hold-down bracket of the battery if your car has one.
Now, disconnect the black(negative) terminal at first. Then remove the red(positive) terminal.
Take the old battery out.
Install the new battery and connect the wires.
Reattach the hold-down bracket and you are done.

The steps of replacing the battery are quite simple and easy. You can also follow this video to replace your Audi battery.

Cost:

A new battery can cost anything between $50 to $200. This price depends on the type and size of the battery. Professional help for the replacement process will cost about $20 to $75. So the overall cost will be between $100 to $300.

Battery Terminal Corrosion:

The battery terminal corrosion can also hinder the charging mechanism of any Audi car. Corrosion creates a barrier in the flow of electricity. As a result, the battery does not get charged even if the alternator supplies electricity.

Solution:

Cleaning the corrosion can solve this problem. Cleaning the terminals is not as complex as cleaning the FCW sensor.

Make a solution with baking soda and water. Apply the solution to the corrosion spot of the battery terminal and rub the place with a brush. This should get rid of the corrosion.

Worn Out Alternator Brushes:

Alternator brushes make electrical contact with the alternator. The brushes must be fresh and clean to maintain this contact. But they can be pretty worn out with time. As a result, the electrical circuit gets broken and the alternator can not charge the battery.

Solution:

The alternator brushes can be cleaned if they are still usable. Cleaning them will ensure the charging of the battery. A cloth or soft brush wetted with methylated spirit can be used for the cleaning. Rub the brushes with the wetted brush. Make sure to clean the brush housing too.

But sometimes they might be worn out beyond repair. Then the brushes are to be replaced. However, a new alternator brush costs between $5 to $25 only.

ECU Problem:

The ECU is responsible for maintaining the correct voltage and supplying current to the alternator and battery. The charging process of the Audi will fail if the ECU doesn’t work correctly.

Solution:

ECU is a very complex unit of the vehicle system. So it must be checked by a trained professional. The professional will decide if the ECU is repairable or if a replacement is a must.

Cost:

The price of brand-new ECUs is between $400 to $1400. Anyway, aftermarket or second-hand ECUs are available at a low cost. Prices of second-hand ones usually start from $100 and can go up to $500. And the labor cost for this job ranges between $100 to $300 or more.

Damaged Alternator Voltage Regulator:

The voltage regulator measures the voltage of the alternator output and sends it to the ECU. Then the ECU works accordingly. A damaged alternator voltage regulator will cause hindrance in this process and ultimately stop the charging process.

Solution:

The damaged voltage regulator must be replaced by a certified mechanic. The cost of the regulator is about $40 to $140. However, the labor cost is pretty high and it can be anything between $140 to $240.

These are all the causes and solutions to the problem of the battery not charging due to faulty alternators in Audi cars. The solutions are quite easy just like the solution to the Jeep app not updating. Make sure to follow the procedures properly to avoid unwanted circumstances.

Frequently Asked Questions (FAQs):

How do you know if the alternator is not charging the battery?

You will know if the alternator is not charging the battery from different symptoms of the car. The car not starting or having trouble starting is the most common sign of the battery not being charged. Dimmed lights & air conditioners not working are some important indications of this issue.

What are the signs of a bad alternator?

The signs of a bad alternator are several. Firstly, the vehicle will not start if the alternator is bad. Frequent stallings will also happen. The vehicle will make whining noises after starting if it has a bad alternator. Dimmed lights, the smell of dead rubber, dead battery, etc. are also signs of a bad alternator.

What causes the alternator to fail?

Overuse causes the alternator to fail. Besides that, normal wear, damaged parts, etc. also cause a failed alternator. Leaking fluid and or too much heat can damage the alternator too. Moreover, wrong jumper cables and too much tight serpentine belts are equally harmful to the alternator.

Conclusion

This is all on the topic of the alternator fault battery not charging. Hopefully, now you should be able to find the issue with the battery of your Audi car and solve it accordingly.