Alternators play a crucial role in keeping your car running smoothly. It powers your vehicle’s electrical system and keeps your battery charged when the alternator starts to fail. It causes a range of problems that lead to expensive repairs.
However, if you recognize the signs of alternator failure early, you can prevent your car from sudden breakdowns and expensive repairs.
In this guide, we will explore the top symptoms of an alternator failure, explain how to test it, and share what steps you should take if you suspect a problem.
What does the alternator do?
An alternator is a small yet important device that makes up your car’s electrical charging system. The alternator converts mechanical energy from your car’s engine into electrical energy. It charges the battery and power system, such as headlights, radio, power windows, and dashboard electronics. In short, without a functioning alternator, your car’s electrical system wouldn’t operate properly.
A good alternator delivers consistent electrical power, keeping your battery fully charged and your car’s electronics running smoothly. It operates quietly without flickering lights or performance drops, even under heavy load.
A good alternator has the following features:
- It provides a stable voltage output for consistent power flow.
- It helps efficient battery charging during all driving conditions.
- It is built with durable materials to resist heat, wear, and corrosion.
- It operates smoothly and quietly without vibrations or noise.
- It is usually equipped with an effective cooling system to prevent overheating.
- It uses high-quality bearings and diodes for long-lasting performance.
- It includes a built-in voltage regulator to avoid overcharging.
- It delivers steady power under load, even with multiple systems running.
What happens when the alternator fails
When the alternator fails, your vehicle starts drawing power solely from the battery. As a result, your car’s battery drains and stops running entirely. That’s why catching the signs of a bad car alternator early is so important.
Top signs of alternator failure
A failing alternator can display several warning signs before it completely gives out. Here are the eight most common indicators you should watch for:
The battery or warning light appears on the dashboard
The most obvious sign is the red battery-shaped warning light on your dashboard. Flicking lights are important to notice if you don’t want the problem to get worse.
But this doesn’t always mean the battery is bad. It can also indicate alternator problems. If this light flickers or stays on even after restarting the engine, it’s time to test your alternator.
Dim, flickering, or overly bright lights (headlights, dash lights)
Another important sign of a bad alternator is a dim headlight or dashboard light. If your car’s headlights or dashboard lights flicker when the car is idling or become too bright when you press the gas, your alternator might not be giving a steady power supply.
This is a common sign of a bad car alternator, and you should replace it as soon as possible.
Dead battery or frequent jump-starts required
A weak alternator fails to charge the battery properly. You might notice that your car frequently needs jump-starting or that the battery dies even though it’s new. If this keeps happening, alternator testing is essential to rule out a charging system issue.
Usually, when internal components like brushes, bearings, or diodes wear out, they reduce the alternator’s ability to produce current. More often, an aging alternator loses efficiency over time due to heat, where there are resistances.
Sluggish or malfunctioning electrical accessories
Did you notice your power windows move slowly or your radio cuts out? It’s a sign of malfunctioning accessories, and points to inconsistent voltage from a failing alternator.
This symptom often shows up before a complete alternator failure. That’s why you should act promptly and either repair it yourself or hire a professional mechanic.
Strange noises under the hood (whining, growling)
If you hear whining, grinding, or growling noises coming from under the hood, it could be the alternator bearings wearing out. If you ignore them, it can lead to a complete breakdown.
Burning rubber or electrical smells coming from the engine area
An alternator has a job that involves heat, and it can burn easily. A bad alternator overheats and smells like burnt rubber or hot wire. This may happen if the alternator belt slips on the pulley or the wires overheat. This is a clear sign of alternator failure. If you notice this smell, turn off the engine immediately and have it inspected.
Engine stalling or difficulty starting the car after the battery is replaced
Car engines fail to start because of only two reasons it could be either a bad battery or a bad alternator. Even after replacing a weak battery, if your car struggles to start or stalls unexpectedly, it’s likely the alternator isn’t charging the battery correctly.
What to check when you suspect alternator failure
Sometimes we suspect that our car has a particular problem, but it turns out later that it was not what we thought. If you think your alternator is the issue, there are a few steps you can take before heading to a mechanic.
Test battery voltage with the engine running
You can test your car’s alternator by testing the battery voltage when your engine is running. You can use a multimeter to measure the battery voltage.
A healthy alternator should produce between 13.8 to 14.4 volts while the engine is running. If the reading is lower, it indicates that your alternator isn’t charging the battery effectively.
Inspect the drive belt, connections, and alternator mounting
Sometimes, the issue isn’t the alternator itself but a loose belt or corroded connections. You should check for cracked belts or frayed wires.
Here are the specific steps to check for a loose belt or corroded connections around the alternator:
- Turn off the engine and disconnect the battery for your safety.
- Carefully inspect the alternator belt for cracks.
- Check belt tension by pressing on it. It should move about half an inch, not more than this. If it moves further, it means the belt connections or loose.
- Look at the alternator mounting bolts and make sure the unit is tightly secured and not shifting.
- Examine all electrical components at the alternator for rust correction or loose fittings. If you find any corroded parts, clean them with a wire brush or a mix of baking soda in water.
- Finally, tighten all the bolts and connectors from before reconnecting the battery double double-check it, and start the engine to test it.
Recognize when it’s more than the battery
It is often observed that even after replacing the battery, you can still face dim lights when the week starts or warning lights. It’s a big sign that your alternator is failing, and it’s not the battery. You should act immediately and get it replaced before it turns into another expense.
The smart move as a motorist is to know when you should take the car to a mechanic’s shop and let the experts handle this.
FAQs
How long can you drive with a failing alternator?
You can normally drive for a short distance for around 20-30 minutes with a failed alternator. However, it depends on the battery charge and vehicle type. If you continue to drive with a failed alternator, it can damage the battery and other electrical systems in your car.
Can a bad alternator drain the battery completely?
Yes, a bad alternator can completely drain the battery. When an alternator is not in good condition, it fails to charge the battery and causes parasitic drain.
When an alternator stops charging the battery, it quickly runs flat once the engine is started, as it becomes the sole power source for the car’s electrical system.
How much does it cost to replace an alternator?
The average cost to replace an alternator ranges from $300 to $800, depending on your car model and labor rates. However, luxury vehicles can cost even more.
Can a failing alternator cause other electrical problems in the car?
Yes, a weak alternator can cause inconsistent voltage, leading to flickering lights, radio issues, and malfunctioning sensors. These problems can affect your car’s electrical system performance.
Conclusion
An alternator is one of the most important parts of your car’s electrical system. It powers up your car’s battery and other parts of the electrical system. Just like other parts of the car, your alternator also has a shelf life.
If you notice any sign of alternator failure, you can test your alternator and get it repaired timely manner to avoid complete breakdowns. This blog post guided you on common signs of alternator failure and tips on how to test an alternator for its health.
