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Car Will Not Start ¶ 

Car will not start or takes a long time to start

How to check if the Battery is functioning ¶ 

Before considering issues with the alternator, it is worthwhile to check to see if your battery is properly charged and generating a voltage. One way to check to see if your battery is functioning or faulty is to test whether there is a voltage difference between the positive and negative terminals.

How to Test if Your Alternator is Generating Power ¶ 

The best way to test if your alternator is working is by using a voltmeter.

For more a detailed overview of the components in alternator, please refer to the following website.

Damaged Stator ¶ 

If your alternator and battery are functioning correctly but your car will not start, then you may have a problem with your wiring. A wire may have come undone, causing an open circuit which prevents the battery from being charged.

The loose wiring may be due to a damaged stator. The stator is a cylindrical series of copper windings that uses magnetic induction to generate alternating current from the rotation of the car rotor. Please refer to this guide on information on how to inspect and replace a damaged stator.

Warning Light ¶ 

Front dashboard warning light remains lit when turning on the ignition or keeps blinking on and off

Voltage Regulator Not Converting Energy ¶ 

The voltage regulator is responsible for adjusting the voltage of the DC current created by the alternator's rectifier. The DC current can then be used to recharge the car battery. If the warning light on the dashboard remains lit after the engine starts, the voltage regulator is likely unable to control the voltage of the DC current generated. This results in a car that can be driven, but will quickly lose electrical power during use. It may also leech power from the battery, decreasing its charge.

Replacing the Voltage Regulator ¶ 

Replace the voltage regulator by first taking out the screw at the bottom of the brush assembly (this also involves removing the screw that holds the lead into the grounding screw). Swap the voltage regulator for a new one and replace the screws that were taken out to remove the regulator. Check to make sure the diodes are receiving the right current by using an ohmmeter.

Dim Lights or Flickering Lights ¶ 

Front headlights appear dim when car is idling but brighten after an increase in RPM

Malfunctioning Voltage Regulator ¶ 

Dim lights and sluggish electrical components are a likely sign of alternator malfunction, particularly of the voltage regulator. See the above section to learn how a voltage regulator controls output voltage and refer to this guide to replace the faulty voltage regulator.

Damaged Diodes Within Rectifier ¶ 

In addition to the voltage regulator, it is also possible that the alternator bridge rectifier is damaged. This can occur if the diodes responsible for converting AC to DC are disconnected or damaged.

Replacing the Rectifier ¶ 

The rectifier receives AC current generated within the windings of the alternator's stator and uses a series of one way diodes to split the current into positive and negative DC current. The rectifier then transfers this DC current to the voltage regulator, where it is eventually reconnected to the car battery. Replacing a faulty voltage bridge rectifier assembly may help the electronics of your vehicle function correctly.

Weak or dead battery ¶ 

Car will not start or takes a long time to start

How to check if Battery is functioning ¶ 

Before considering issues with the alternator, it is worthwhile to check to see if your battery is properly charged and generating a voltage. One way to check to see if your battery is functioning or faulty is to test whether or not there is a voltage difference between the positive and negative terminals.

How to Test if Your Alternator is Generating Power ¶ 

The best way to test to see if your alternator is working is by using a voltmeter.

For more a detailed overview of the components in alternator, please refer to the following website.

Damaged Stator ¶ 

If your alternator and battery are functioning correctly but your car will not start, then you may have a problem with your wiring. A wire may have come undone, causing an open circuit which prevents the battery from being charged.

The loose wiring may be due to a damaged stator. The stator is a cylindrical series of copper windings that uses magnetic induction to generate alternating current from the rotation of the car rotor. Please refer to this guide on information on how to inspect and replace a damaged stator.

Burning Smells ¶ 

When the car is running there is a burning or foul smell in the air

Loose belt ¶ 

This could be an issue with the belt which provides mechanical rotational energy from the engine to the shaft of the alternator. The belt may not be tight enough and cause slippage between the belt and the shaft. This can usually be fixed by tightening the belt.

Screeching or Whirring Sounds ¶ 

The vehicle makes a whining or squealing noise while in motion

Worn Brushes in the Alternator ¶ 

Weird sounds can be an indication of worn or faulty brushes within the alternator. The only way to know whether the brushes are causing the noise is to take apart the alternator and inspect the brushes. Alternator brushes are usually positioned at the rear of the alternator and are difficult, if not impossible, to see. The best way to tell if alternator brushes are bad is by doing voltage checks. Please view the following website for a detailed description of how to diagnose a faulty brush.

Replace the brushes by first unscrewing them from their respective channels and then clean the part of the armature shaft that the brushes connect at. Make sure that the springs of the new brushes are directly at the back, in which they push into the brush slot.

Loose Belt ¶ 

The alternator is driven by a belt which provides the mechanical rotational energy to the alternator from the engine. If the belt is not tight enough, the belt can slip on the pulley attached to the rotor in the alternator and create a squealing noise.

If you notice that the car squeals when it is cold or wet, this strongly indicates that the belt is loose. Although this is not a problem with the alternator directly, it can be a common cause for squealing.

Please view the following websites for a detailed description of how to diagnose and adjust a loose belt.

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