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What is an Alternator?

In a car engine, the alternator is used to charge the battery and power the car’s electrical system when the engine is running. An alternator works by turning mechanical energy into electrical energy, in this case, the energy created by the car’s combustion engine is used to create alternating current to power the electrical systems. Alternators replaced the use of conventional dynamos in the 1960s and, being lighter, cheaper and more rugged, they helped pave the way for car manufacturers to introduce many of the innovations we now consider standard.

Alternators work using electromagnetic induction, employing a rotating magnetic field within an armature coil to generate electricity. Modern alternators found in vehicles use a compact layout that improves air cooling with distinctive radial vents that enclose the fans at each end, allowing greater power generation from a smaller machine. This ensures that the demands of modern car electronics can be met without the need for very large power sources.

It is also worth noting that modern hybrid vehicles replace the alternator with one or more motor/generators (M/Gs) that, alongside battery charging and engine starting, provide some or all of the power to the wheels. These are often accompanied by large storage batteries and significantly more powerful electronic controls.

Warning Signs Relating to Alternator Issues

Warning Light

Common to most modern vehicles, the warning light found within the dashboard is often the first indication that your alternator is experiencing issues. Usually displayed as an illuminated battery sign, this light is linked to the systems that monitor the voltage output of the alternator. If this light is illuminated, it may be a sign that your alternator is not working to its full potential. This is most likely to happen as you increase the load on the alternator through the use of electrical components. A briefly flickering warning light is generally not a problem, however, if this light remains illuminated for long periods, then it should be addressed.

Dim Lights

As your alternator struggles to keep up with the loads placed upon it, you may notice a number of electrical issues present themselves. Most modern computers within cars have a priority list that ensures the continued safe operation of the car in the event of alternator failure. As a general rule, this means that less crucial electronic components, such as heated seats and your car radio, will be sacrificed in favour of safety elements like headlights. This means that, whilst you may not notice the loss of lesser components, should your headlights suffer regular and prolonged dimming, it is almost certainly an alternator issue.


Sight, sound and smell—invaluable tools in determining issues in any car. Firstly, many alternator issues can be solved simply by looking under the bonnet and ensuring that the belt is correctly attached and still in good condition. Any cracking or excessive wear may also impair functionality. At this point, it is also worth checking the condition of your cables and connectors.

Any strange sounds or smells coming from your engine should also be investigated. A “growling” or “whining” noise may accompany an alternator failure, so too the smell of burning rubber or hot wires. Checking the alignment of the belt is again important, although an overheating alternator may also cause similar symptoms.

Discharged Battery

A discharged battery is not necessarily an alternator issue. However, if you find your battery is regularly drained, particularly after re-charging or replacement, you may need to use a test to identify the problem. Thankfully, this is relatively easy. In order to pinpoint whether it is your battery or your alternator causing the problem, simply jump start your engine and remove the cables as soon as possible. Should the car continue to run, then it is likely a battery issue. However, if the engine cuts out relatively quickly, then it is more likely to be an alternator issue.

Buy Alternators Online from Mister-Auto

If you identify a problem with your alternator and you require a replacement, then Mister-Auto is your go-to supplier of great value parts for a comprehensive variety of makes and models of car. Established in 2007, Mister-Auto is among the leading automotive websites in Europe, stocking over 300,000 products across all major brands for both domestic and foreign vehicles.

In addition to this, Mister-Auto makes buying alternators and other parts quick and easy. With the option of free shipping and flexible payment plans, alongside discounts of up to 60% and an easily navigable website, Mister-Auto allows you to concentrate on keeping your car in great condition. Browse our website today and find the parts and accessories you need at great prices.

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