Alternator (Charging Dynamo) Faults

What Happens If the Alternator Fails?

If the alternator (charging dynamo) fails, not enough electricity is produced, and the battery weakens or drains completely. Common alternator faults include the following:

1- Worn-out alternator brushes: If the alternator’s brushes are worn out or depleted, it can’t produce electricity, so the charge warning light stays on continuously.

2- Noise coming from the alternator: A noise coming from the alternator can indicate that the bearings have failed. Especially if a whining noise increases when you press the accelerator, this may indicate an alternator fault.

If this situation isn’t addressed, the bearings inside the alternator can disintegrate and the alternator can seize. When the alternator seizes, the drive belt will stop turning. Since this creates a problem in transmitting speed from the engine, the drive belt can snap. If the drive belt snaps, the coolant pump won’t run and there will be no water circulation inside the engine. As a result, your vehicle will overheat.

3- Voltage regulator fault: If the voltage regulator fails, excess voltage is sent to the system and the car’s bulbs blow frequently.

4- Diode fault: In this case, the diodes can’t convert alternating current into direct current.

5- Alternator belt breaking or loosening:

If the alternator belt breaks, you may run into situations like these:
1- Since alternator belts usually also drive the water pump, if you keep driving, the engine temperature will rise.
2- If the alternator belt also drives the power steering pump, steering will become stiff.

How much tension should the fan belt have?
The fan belt should be able to flex 1-1.5 cm.
If the fan belt is too tight, the bearings and races can fail.
If the fan belt is too loose, enough voltage cannot be produced.

How Can You Tell If the Alternator Has a Fault?

While the engine is running, if the headlights dim when you take your foot off the accelerator, the battery may be weak. The alternator may not be producing enough electricity. The fan belt may be loose.

If you see the warning light above, this can also indicate an alternator fault.

This light is connected to the computer system that monitors the alternator’s output voltage. If the alternator’s voltage output is outside the set limits, this icon appears. If the voltage is within limits, this icon does not appear.

In the early stages of an alternator problem, the light may flicker on and off intermittently, or it may only come on when you run accessories in the vehicle. For example, you turn on your wipers and notice the warning light comes on. When you turn the wipers off, you notice the light goes out.

Dim or overly bright headlights and dashboard lights:
If your vehicle’s headlights are shining weaker than they should, or brighter than they should, this indicates that the alternator is not working properly.

All of these situations could be signs of an alternator fault, but you may also experience things like the speedometer and tachometer stopping for no reason, or power windows moving up and down more slowly.

In recently manufactured vehicles, there is a program that determines where electricity is sent first when there’s an alternator problem. This program operates by prioritizing your safety. For example, before the headlights dim and shut off, heated seats will be turned off or the radio will be disabled.

Note:  In some cases, the reason the system isn’t getting enough power may not be an alternator fault. The problem may be in the battery.

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