An alternator is the charging component of a car that restores electricity to the battery and provides power to the vehicle's electrical network.

Its sole operation is to turn mechanical energy—derived from the combustion engine—into an AC electrical current. The electricity is then supplied to the car's power accessories and for the recharging of the battery simultaneously.

Based on this short definition, it's a no-brainer to understand the ramifications when an alternator fails to function.

This article will discuss the telltale signs of a faulty alternator. If any of these occur, it would be wise for you to have a mechanic check the vehicle immediately.

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A failing alternator can't properly recharge the car battery. Hence, the battery won't have adequate amperage to power up the engine. Forcing it to start, on the other hand, will likely drain the battery empty and damage it.  

This domino effect is common among those who suffer from experiencing a busted alternator. 

It's one thing when the battery is dead because it reaches the end of its lifespan. It's another when it's still new and yet drained. 

If you didn’t forget to turn off the headlights, and no other accessories were consuming the battery power, then it's an indication that the alternator is probably not working.

Aside from the fuel, your car depends on the electricity the alternator generates. The immediate effects of having a faulty alternator are the intermittent fuel injection in the combustion chamber and the misfiring of the spark plugs. This causes the engine to stall. 

A stalling engine affects the overall mechanism cycle of the vehicle and could potentially damage the other components.

When the electric current becomes weak, it affects the performance of the accessories. You may notice the power windows not rolling (or slide slower than usual), air conditioning systems malfunctioning, and the horn beginning to sound hoarse.

Our initial suspicions would be that these power accessories are going through some glitches. Although individually, these car features occasionally break—some parts need replacing, wires become corroded, etc. 

When they all act up together, however, there's probably just one causation behind them all—a broken alternator.

Modern cars have dashboards equipped with sensors that display any anomalies in the vehicle’s system. When the battery warning light turns on in addition to all the odd occurrences mentioned above, it could be that the cause of the problem is the alternator not performing.

People usually interpret the warning as having something to do with the battery itself. After all, the sign resembles the likeness of it. However, the reason this particular warning light turns on is when the system's sensor detects changes in the electrical voltage. 

As the alternator under-delivers a power output that isn’t in the range of the preset values, the icon in the dashboard lights up.

Sometimes, this can happen erratically as the warning light turns back off. The inconsistency transpires when the current from the alternator goes back to producing electricity within the acceptable range. 

It doesn't mean, however, that everything is ok. It only indicates that some aberration in the alternator's performance is already beginning. It's just a matter of time before things turn out for the worse.

Unsteady Headlights and Dim Interior Lights

Alternator troubles also manifest through dim interior lights and the unsteady brightness of the headlights. These signs occur together most of the time.

If your vehicle's light goes from pale to bright and vice versa on a regular or random interval, it’s most likely that the electrical system has become faulty. When this happens, the primary defective component is the alternator. 

Insufficient production of electric current causes the irregular shifting of the brightness of the lights. Your car is trying to compensate for and balance the electricity distribution throughout the electrical network.

Another way of confirming that the alternator is causing the problem is when you use another accessory in the car that takes up electricity. Say, for example, you turn on the audio system or roll down the power windows, did it make the lights flicker? By employing other features, you’re adding power load to the system. Doing so narrows down the likelihood that the problem is indeed the alternator.

A failing alternator makes an unusual noise that’s distinct from the engine sound. The noise would likely come from the serpentine belt and the component's worn-out bearings.

The serpentine belt is the rubber strap that connects the alternator to the engine. When this conveyor belt deteriorates and wears out, it creates a squeaking sound.

As the belt dilapidates, it also misaligns and disproportionately stretches. These add to the factors that make the alternator fall short of generating the right amount of power. The alternator bearings degrade due to the metal-to-metal friction, creating a buzzing noise as well.

Over time, the entropy of these materials becomes severe to the point that the alternator can no longer serve its purpose.

So, when you hear unusual noises coming from the engine bay of your car, it's best to always go for a checkup immediately.

A broken alternator makes a car unfit for the road. While most people will try to apply temporary solutions, like jump-starting their vehicle, such an overriding measure might damage other parts of the car (fuel pump, electric-powered steering wheel, etc.).

So if you're on the road and your car's alternator gives up on you, it’s best to ask for assistance (towing services) and bring your car to your trusted mechanic before irreversible damage to other parts of your vehicle ensues.

If you opt to repair the broken alternator, the average budget you'd have to prepare ranges from around $300–$400. The actual price could go higher, depending on the car type and how challenging the repair process would be. Plus, mechanics don't have a uniform rate.

If you choose to buy a new alternator, on the other hand, prepare to shell out an amount between $600–$800.

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Signs of a Malfunctioning Alternator