The car alternator, its usefulness and operation -canalMOTOR

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5 min read | The alternator is the element that provides electricity to the vehicle when it is running. It works by transforming mechanical energy into electrical energy, in order to provide it to all the components of the vehicle in operation.

Actually, its operation is quite simple since it is simply a device that incorporates a mechanism that internally generates alternating current when turning through an electromagnetic induction process.

Obviously to rotate, the alternator connects to the engine via a service strap that gives it the necessary impetus for its operation.

Indeed, and in a very synthetic way, we can say that the alternator is a simple device that was created to provide electrical current that is used to maintain the charge of the batteryalso supplying current to all the electrical systems of the vehicle that require it (lighting, air conditioningetc.).

 alternator strap

Source: World Motor Magazine

It is a subsequent development of the dynamos, which were replaced in the automotive industry in the 70s by alternators, as it is a much more advanced and capable mechanism.

Currently, due to significant technological advances, vehicles have incorporated a huge number of components that require electrical power, so current alternators are much more sophisticated and powerful and thanks to them all these new systems work correctly, despite their demanding electrical energy needs.

parts of an alternator

Basically the alternator block is made up of 5 generic parts:

exploded alternator

Source: World Motor Magazine

  • Pulley:with which the mechanical power from the heat engine is received, through a belt that is generally “poly V”. It is attached directly to the shaft of the alternator in order to move the rotor inside the block, in addition to moving the fan that most of the latest generation alternators available normally also mount inside.
  • Rotor (inducer): It is the only moving part of the alternator and is made up of an electromagnet that receives current from the regulator through slip rings that are also located on the shaft, thus producing a magnetic field that makes the “stator” coils react in the fixed part, thus producing the necessary electrical current.
  • Regulator: It is the mechanism that is responsible for maintaining a maximum output voltage of the alternator (14.5 volts) and also for regulating the amps that the battery needs at all times.
 Alternator belt detail

Source: World Motor Magazine

  • Stator (armature): It is located in the fixed part of the alternator and contains the three-phase winding. Depending on the alternator model, it is star-shaped or even triangle-shaped.
  • Diode bridge rectifier:At the end of the alternator’s operating cycle, there is this rectifier bridge that converts the generated current, which is alternating, into direct current, making it useful for use in the car and all its electrical systems.

Summarizing all of the above, the alternator is the mechanism that produces alternating current through a drive mechanism that is driven directly by the combustion engine with its motor rotation, and generally linked by a belt that is what gives life to the whole process.

At boot time the vehicle, the alternator rotor coil is supplied with currentthus beginning to rotate, so that from this very moment it begins to generate energy.

When the engine stabilizes in its normalized management, the regulator stabilizes and feeds itself with the energy produced by the alternator itself, thus turning off the indicator light on the instrument panel. In the event that said indicator does not turn off after starting the vehicle, this would indicate that there is no power output from the alternator, so the vehicle will only have electricity until the complete battery depletion.

It is interesting to know that If the indicator light on the instrument panel flashes quickly, it is because there is a lack of charge. (possibly regulator failure) or because alternating current is being obtained by having the diodes perforated in the rectifier bridge. If this or another pilot jumps on the control panel of your vehicle, it is best to stop and call the MAPFRE Car Insurance that has roadside assistance, so you will avoid a greater evil.

 alternator rotor

Source: World Motor Magazine

For correct operation of the alternator necessary check that the 12 volts from the battery reach the input of the regulatorin addition to verifying that the diodes of the rectifier bridge are not cutsince in any case the alternator current would not come out, even if it generated it correctly.

Secondly, slip ring brushes may even be worn, preventing current from entering the inductor (or rotor). All these operations and checks must be carried out by professionals in any case.

 modern alternator

Source: World Motor Magazine

But to relieve users of concerns with all this alternator complexity, most current cars have an electronic control unit to regulate the alternator, thus turning on the light indicator directly and not being able to carry out the previous traditional diagnoses, although it is possible to resort to the diagnosis machines in the workshop to find out exactly what the problem could be in the event of an alternator malfunction.

world engine

Journalist Specialized in Automotive in world engine

The World Motor editorial team joins the channel as an expert in the automotive sector. Thanks to its long history and years of experience, its content on car and motorcycle models, in addition to road tests and all the news in the motor world, exceed the expectations of the most demanding reader in terms of accuracy and depth.

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