A faulty alternator not only makes the safe operation of a car impossible but can significantly damage the entire vehicle. For instance, faults in the electrical part of the alternator lead to severe deviations in onboard voltage which cause a high probability of microprocessor failure. Thus, alternators are a vital component of your vehicle’s electrical system, and any issue needs to be addressed immediately.
This article covers the importance of alternators and their replacement costs.
The alternator is one of the main components of the car’s electrical system, which transforms the mechanical energy from the engine shaft into electrical power and supplies it to the onboard power system.
The following vehicle components and assemblies depend on the proper and uninterrupted operation of the alternator:
Alternators come in several types and differ in terms of fuel, size, power, and types of electric current generated:
The stator and the rotor are considered the main elements of a car alternator. The stator is a package of steel plates assembled in several blades along its circumference and wrapped with copper wire; each blade has a strictly defined number of coils.
The rotor consists of a steel lug (shaft) with wedge-shaped projections and notches. This shaped shaft is wound with copper wires and has a certain number of turns on each shaft. It is called excitation winding. Its leads are connected to the contact rings. When the rotor rotates, an electric voltage is generated in the stator.
The standard voltage in the alternator of a modern car is 13.8 to 14.6 volts. It is sufficient for the regular operation of electrical devices, including battery charging. If the voltage is lower, the battery won’t charge, and the onboard network will consume your battery and eventually discharge it. The orange or sometimes even red indication on the instrument panel indicates a lack of power. If this indicator appears, stop the vehicle, switch off the engine, and call a service technician.
You can continue driving at your own risk, but in this case, all electrical devices and equipment will be powered by the battery, and in the event of battery failure, you will have to buy a new one.
A sure sign of a broken alternator is when the car's engine does not start smoothly. The second symptom becomes noticeable when it is dark. Car headlights go dim, or the degree of brightness changes depending on engine speed and load on the electrical system.
A lit or blinking battery icon on the dashboard indicates that your car has a severe problem —the battery is not charging correctly.
Other signs include a whistling drive belt, belt overheating or collapse, a ringing or rustling sound from under the hood, or an electric hum.
If you have concerns with your alternator, you can use a multimeter (an electronic measuring device) to test the alternator’s performance. First, maximize the vehicle’s voltage load by turning on the vehicle and all of its electronic accessories (climate control, headlights, radio, etc.). Then, connect the multimeter’s red probe to the positive battery terminal and the black probe to the negative battery terminal. If it displays a reading less than 13.5 volts, then you should consult a professional to confirm the alternator issue.
Not everyone has a multimeter handy, so if you do not have the tool or the comfort to execute the test on your own, some shops like AutoZone offer a free alternator test service.
Although some automotive parts have relatively predictable lifespans, estimating how long an alternator will last is more challenging. One can expect an alternator to last 7 to 10 years or about 100,000 to 150,000 miles. Given this is a general range, some will never have to replace their alternator while others may go through multiple alternators on the same vehicle. Typically, the alternator’s maximum amp output impacts its lifespan. A vehicle’s electrical elements regularly reaching close to the maximum amp output is indicative of an alternator that won’t last as long. Thus, it is worth asking a professional if a higher amp alternator is a more logical fit to support your vehicle’s electrical performance.
Alternator replacement costs depend on the model. One can expect to pay $100 to $350 on average for the part alone. However, some luxury models may require alternators in the $500 to $700 range. In most cases, costs will average between $350 to $400 for the alternator replacement if no other parts need to be changed. You can plan to add another $20 to $50 to your bill if the serpentine belt, also known as the alternator belt, has to be replaced as well.
If you decide to go with dealership parts and labor, expect the bill to climb over $500 in many cases. Because the total cost depends on the vehicle, you can expect to pay anywhere between $350−$900 for an alternator replacement.
In some situations, alternator labor and parts can surpass $1,000. While these estimates can be a hard pill to swallow, there are luckily strategies to limit the impact on your wallet. There are two primary ways to reduce costs: purchasing a rebuilt alternator and installing the alternator yourself.
Rebuilt alternators are comprised of original equipment replacement parts. Additionally, bushings, bearings, brushes, and other wear items are replaced with new components during the rebuilding process. When choosing a remanufactured alternator, select one with at least the same amp rating or higher as the one you are replacing. These alternators are rebuilt by many of the same companies that manufacture new alternators and typically come with a warranty.
You can conduct an alternator replacement as a DIY if you are relatively skilled with tools. Considering labor costs alone could be a few hundred dollars, this is another way to save money. Although not as complex or as labor-intensive as other DIY auto repairs, an alternator replacement can still take a few hours to complete. The high-level steps of alternator replacement include turning the vehicle off and ensuring all electrical components are off, disconnecting and removing the battery, removing wires from the rear of the alternator, removing the old alternator, and installing the new one.
Regardless of the overall technical condition of the power units and assemblies, the reliability of a vehicle on the road depends on a few components, which at first glance seem to have a secondary function. One such component is the alternator. Practice shows that the car engine can operate without an alternator, but this is not recommended, and it is essential to know when you must replace it.
Matt Yantakosol is a lifelong automotive enthusiast and former consultant focused on the consumer aspect of the industry. He has traveled to New York, Detroit, Chicago, L.A., Paris, Geneva, Frankfurt, and Tokyo Auto Shows to track and observe the newest industry innovations. In addition to JDPower.com, Matt's writing has appeared on Pcarmarket.com.
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