Skip the auto shop - Our mechanics make house calls

Q: How Does the Alternator Work in Your Car?

asked by on

How does the alternator work in your car?

A: If the vehicle’s battery is the heart, its ...

If the vehicle’s battery is the heart, its alternator would be comparable to its lungs. Both systems must work together to start and keep your vehicle running for years. The alternator is responsible for supplying power to all electrically powered components in a vehicle while the motor is operational. Before the engine starts, this responsibility falls on the battery. Once the driver turns the key and starts the motor, the alternator is activated and takes over for the battery.

How does an alternator work?

The alternator is typically installed in the engine compartment and is powered by a belt called the serpentine belt. In some cases, the alternator has its own belt called the alternator belt. When the engine spins over, a series of pulleys that are attached to the engine’s crankshaft are spun, which in turn spins the belt that is attached to another pulley on the alternator. The pulley attached to the alternator is connected to a needle bearing that spins around a series of metallic coils and generates electricity. There are also voltage regulators that control the amount of electricity produced. The electricity is distributed from the alternator to a series of relay switches, fuses, and connectors that supply power to components on the vehicle. The alternator is constantly working to generate electricity while the engine is running. Due to this fact, there are several factors that impact the lifespan of the alternator, which makes it very difficult to predict exactly how long it should last on a car, truck, or SUV. In some cases the alternator will work as long as you have the vehicle. In general however, the alternator should last anywhere from 50,000 to 100,000 miles on most domestic and import cars, trucks, and SUVs.

There are a few signs that might alert you that the alternator is wearing out, including: * The headlights seem dimmer than usual * Dashboard lights are not as bright as they should be * The ALT or GEN light illuminates on the dashboard * Accessories such as radios, AC and auxiliary switches don’t work as well

These symptoms are common with an alternator that is wearing out. If it breaks or the alternator belt is broken, the vehicle will quickly drain power from the battery and eventually shut the vehicle off or make it impossible to start. If this occurs, you’ll need to contact a local ASE certified mechanic and have them complete an alternator replacement or alternator belt replacement to get your vehicle back on the road.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car won't start

Hi. This is a pretty common problem with you vehicle. After the engine is shut off, the fuel pump bleeds off pressure. Then, when you go to start the vehicle, extended cranking is required to build the pressure back up....

Q: squeaky idler pulley

Replace the entire tensioner assembly since the tension is what caused the pulley to go bad. You should also replace the belt if any damage is noted.

Q: Electric/Engine problems

In looking at wiring diagrams for your car, I don't see a connection between the speakers and the interior blinkers. This doesn't mean there isn't one. Same goes for the lack of power. To figure this out I would begin...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...