Jump to content
The Motorists' Guide

Guide to Alternators

Recommended Posts

What is an alternator?

A car alternator converts mechanical energy into electricity, which is then used to charge the vehicles battery and help run vehicle electrical systems whilst the engine is running. Within the alternator is a rotating magnetic field where alternating current passes through a rectifier to be converted into direct current which allows a consistent voltage to be passed through the cars electrical system and battery terminals. To support the alternator is a volt regulator which monitors the electrical current passing around the vehicle and on modern vehicles can be found within the ECU. 

Where is an alternator located?

The alternator is located in the engine bay connected to a belt driven by the engine. 

Does it go wrong? 

Yes, they do go wrong which can manifest itself in various ways

  1. You find your car has a dead battery which is caused by the alternator not charging the battery when driving
  2. The car struggling to start due to the battery being weak due to not being charged by the alternator whilst driving. 
  3. Whilst driving a red battery light may appear on the dash to indicate an issue with the battery charging system. 
  4. Whilst driving with lights on you will find them getting progressively dimmer. 
  5. Electrical systems such as electric windows or locks may start to work intermittently or stop working completely.  
  6. Funny engine noises. if the bearings within an alternator start to fail they can cause it to make unusual noises or become louder in its operation. 

Is it easy to replace? 

Before replacing the alternator the first thing you should do is have it tested to see whether it s producing enough electricity for it to power the vehicle. if it has failed then replacing it is your only option. Dependent on your skill level this is a job that can be done at home and will reguire you to: 

  1. Disconnect the battery
  2. Locate the alternator and jack the vehicle up for access if required. 
  3. Unclip the electrical connector attached to the alternator. 
  4. Undo the bolts holding the alternator in place along with removing the belt. 
  5. Refitting in the reverse order. 

Hope you found this guide useful. Let us know in the comments section. 

Article written by SteveQ

Link to comment
Share on other sites

  • Create New...