How Can I Tell If My Alternator Is Bad?

How do I know if it’s the battery or the alternator?

If the engine starts but dies immediately, your alternator probably isn’t keeping your battery charged.

If a jump starts and keeps your car running, but the car can’t start again off of its own power, a dead battery is likely your answer..

Can an alternator be bad and still charge?

If it’s still sending out a strong charge, the battery is likely not the problem. It’s important to note that once an alternator goes bad the electrical devices will attempt to draw power from the battery, which in turn could cause the battery to die more quickly.

Why won’t my car start but lights come on?

Starter Symptoms This is usually due to battery failure, poor connections, damaged battery terminals, or a dead battery. … If you find that your car starter is the issue of why you have the “car won’t start, but lights come on” situation, you need to replace the starter in your vehicle.

Can a car run with a bad alternator?

The alternator in your car provides power to the spark plugs that ignite the gas in your engine. If your alternator is beginning to go bad there might not be enough power in your spark plugs to start your car or keep your car running.

What sound does a bad alternator make?

Whining and Grinding Sounds If your alternator is failing, you could hear a few abnormal noises. If you hear a small rattling or grinding sound when your engine is running, this could be caused by a loose bearing in your alternator.

How much does it cost to replace alternator?

Waits says the average price to replace an alternator with a remanufactured one is $400, while Gunning adds that a remanufactured alternator on a typical, domestic car, costs about $300 to $500, including parts and labor. The price of a new alternator can run from $500 to $1,000.

How long does a car alternator last?

about seven yearsThe battery’s job is to start the car, and the alternator keeps it running.” Gunning says an alternator typically lasts about seven years — or about 100,000 to 150,000 miles, says Waits. Some mechanics, though, say they typically see alternators last about 80,000 miles.

How do you fix a car alternator?

How to Change a Car AlternatorSave the memory on your vehicle’s preset electronics.Disconnect the negative battery cable.Loosen the belt tensioner.Loosen and remove the serpentine belt.Remove the wiring harness or connectors.Loosen and remove the alternator.Install the new alternator, making sure it fits and aligns with the bolt holes.More items…•

What causes an alternator to fail?

Bad diodes are a common cause of alternator failure. The diodes are part of the rectifier assembly that converts the alternator’s AC output to DC. … A leaky diode also can allow current to drain out of the battery through the alternator when the vehicle is not being driven.

What are the symptoms of a bad alternator?

6 Symptoms of a Failing AlternatorThe indicator light. … Headlights are dim or flickering. … Other electrical failures. … Strange noises. … Car stalls or has difficulty starting. … Battery dies.

Can Autozone check alternator?

Free Testing We’ll check your alternator, starter, battery and more.

Can AutoZone replace an alternator?

Now that you know how to replace an alternator, it’s time to pick up all the tools and equipment you need. For the best prices on name-brand alternators, affordable hand tools, and precision replacement parts, visit your local AutoZone.

Can you disconnect battery to check alternator?

If you’re tempted to test an alternator by disconnecting the negative battery cable, don’t do it. A good alternator may indeed keep the engine running without the negative cable, but this was never a good test. … The second you disconnect the battery, the voltage regulator pegs the alternator to put out maximum power.

Can a bad alternator destroy a new battery?

If you take your vehicle to an auto parts store they may give you a new battery for a few hundred dollars, without running any tests. Don’t make this mistake! A faulty alternator could ruin a perfectly healthy battery, which would put you further back from a solution than where you started.

What happens when an alternator goes out while driving?

The alternator generates power from the engine to run the electric parts of a car. If your alternator dies while driving, you may just stop and be stranded, but a bad battery can also give you problems at low speeds.

What does a bad alternator smell like?

Burning Rubber Smell The alternator works with a variety of belts inside your engine, and if a belt is not turning the way it should, the friction will cause a burning smell. If you catch a smell similar to an electrical fire, you might need to replace or tighten a belt.

Why will my car only start when I jump it?

If jump starting gets your engine started and running, but the car will not start again once you turn it off, the battery is probably the problem. In this case, the alternator is doing its job of keeping the battery going once it has been jumped, but the battery can’t hold a charge when the alternator is shut off.