Alternator

An automotive charging system is made up of three major components the battery, the voltage regulator and an alternator. The alternator works with the battery to generate power for the electrical components of a vehicle, like the interior and exterior lights, and the instrument panel. An alternator gets its name from the term alternating current (AC). Alternators are typically found near the front of the engine and are driven by the crankshaft, which converts the pistons' up-and-down movement into circular movement. To learn more about the basic parts of car engines, some early model vehicles used a separate drive belt from the crankshaft pulley to the alternator pulley, but most cars today have a serpentine belt, or one belt that drives all components that rely on crankshaft power. Most alternators are mounted using brackets that bolt to a specific point on the engine. One of the brackets is usually a fixed point, while the other is adjustable to tighten the drive belt. Alternators produce AC power through electromagnetism formed through the stator and rotor relationship. The electricity is channelled into the battery, providing voltage to run the various electrical systems.

The alternator is about the size of an old-fashioned pint glass and has lots of vents on its aluminium body that allow it to keep cool as it does its job. On one end of it is a pulley around which is a rubber belt. This same belt also goes around another pulley attached to the engine. As the engine turns, the belt turns with it and as it does so, it turns the pulley on the alternator. This pulley sits on a rotating shaft, called a rotor, that goes into the alternator. Look around the lower front and sides of your car’s engine. You’ll spot the alternator because unlike other components, it’s got those vents. You might also see that it’s pivoted at one end. Slackening off the bolt that secures this pivot allows you to move the alternator and adjust the belt. Too slack and it won’t turn the rotor too tight, and it risks damaging the alternator’s bearings.

The rotor is actually an electromagnet spinning inside fixed coils of tightly wound copper wire. These coils are called the stator, because they’re stationary. As the rotor spins, (remember, it’s being turned by the engine) it generates a small amount of electricity from two carbon bushes touching a couple of metal rings. This small charge generates a much bigger charge inside the stator. The electrical charge the stator generates is in the form of alternating current (AC). The trouble is, a car battery likes direct current (DC). The current needs to be rectified, so enter the rectifier. Rather like turning water into wine, the rectifier turns AC to DC. However, the battery likes its DC just so – not too much and not too little. So, to keep the battery happy, the alternator has a regulator that controls the amount of current going to the electromagnetic rotor.

Start your car’s engine. Did you notice that little red battery symbol come on briefly? It’s actually a warning symbol which, if it were to stay on, would indicate there’s a problem with the alternator. If the alternator has still got some life in it, the light may flicker or, if you make it work harder by turning on additional lights, the air con and the wipers, it may stay on. As the alternator really begins to pack up, those same systems may not function properly or stop working altogether. Since so many things are powered by electricity, you’d be surprised what can stop working, including vital instruments. However, it’s likely things will start failing in a pre-determined sequence with comfort features such as heated seats being the first to stop and the headlights, the last. If you pull over and raise the bonnet with the engine still running you might smell the alternator overheating, hear it making a grouching or whining noise or even, if you haven’t had it checked recently, see the rubber belt slipping or flapping about.

When the alternator begins to fail or simply fails, the battery takes over but as we’ve seen, it does not last long. The trouble is, it’s slow death gets mixed up with the alternator’s so it can be hard to tell which is at fault. One easy way is to check the condition of the battery with a voltmeter. Another is to jump start the car. If the car starts and runs but soon stops, it’s the alternator that’s at fault because it’s not generating any electricity. If the car runs OK, the battery is likely to be the culprit. Time for a new one.

The car's alternator performs a simple, but vital job: to keep your car's battery charged. The battery is responsible for starting the car, spark plugs, lights, electrics, and sometimes power steering - quite a job - so it's essential that it's topped up - and that's what the alternator does.

The alternator acts like a small generator: the engine spins it, and the alternator turns that spinning motion into electricity. The most common problems are worn brushes (the component that maintains constant electrical contact with the spinning alternator) and a failing voltage regulator which ensures that the charge is sent to the battery at the correct voltage.

Common signs of car alternator problems include the 'charge' or battery lights flashing on the dashboard, flickering or dimming headlights and interior lights and a growling or whining noise under the bonnet.

A simple way to test an alternator for problems is to do what's known as the headlight test. Park your car with the headlights on or run it in neutral, then rev the engine. If the headlights dim you could well have an alternator problem. A better test is to take your car to a garage, where a car alternator can be tested using a multimeter tool.

Should you experience any problems like those listed above it is important to have the alternator inspected and, if necessary, have the alternator replaced. Always remember to service the alternator as and when stipulated in the manufacturer's guidelines. It is essential that the alternator is kept in tip-top condition, this should contribute to a prolonged and unproblematic alternator lifespan.

Sometimes, the worst part of getting your car fixed is having to bring it to the garage. We are therefore happy to offer our customers a free collection and delivery service If you prearrange a collection, we will pick your car up from your home or place of work and drive it to our premises, carry out all the necessary work (having consulted you) and deliver it back to you at the end of the day.

We are able to tow, jump start or repair your vehicle if you are experiencing problems or broken down for a small fee. If we can't sadly start your vehicle, we can contact a local recovery firm to collect your vehicle for a very competitive price.

Don't want to waste your day off?
You don't have the time to take your car in for a service or repairs?
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Here at Car Services in Reading, we believe that we offer a valuable product with our Free Collection and Delivery Service, we can collect either from your place of work or from your home address. If you are unsure about whether the address you are considering having your vehicle collected from is not within our range, then please do contact us.

Car Services in Reading operate a fleet of pool cars with a dedicated driver, so wherever we are collecting from, we need to be able to leave one of our pool vehicles either in your work car park / parking space, or if in a residential area, we would need to be able to leave our car either at your house or on the road with a permit if required. We would be grateful if you could bear this in mind when booking to use our free Collection and delivery service