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Focus On: Alternators Part One

Focus On: Alternators Part One

If you have ever experienced a battery that just won’t hold charge properly then the problem is likely to be the battery, however, there is a chance that you also have a faulty alternator.

The alternator plays an important role in any combustion engine; it is responsible for making sure that the battery has enough energy to start the engine and, once it is started, it provides power for the vehicle’s electrics. In this series we will take a closer look under the bonnet at the alternator and talk through its function, and what can happen if it goes wrong.

What is an alternator and what does it do?

An alternator takes mechanical energy produced by the engine’s crank shaft and turns it into AC (alternating current) electrical energy, before turning that AC energy into DC (direct current) energy, which is what your vehicle needs. This energy is used predominantly to charge the battery, so that the battery has enough power to provide the electrical surge that is needed to get the engine going every time you turn it on.

Once the main job of getting the engine started is done, the alternator will use the energy made by the engine and convert it into power to replenish the battery as well as power other electrical components of the vehicle while the engine is running. Note that the battery will only power electrical elements when the engine is off, and the alternator is not able to do so.

What about smart alternators?

Smart alternators are also known as ECU controlled charging systems. They work a little differently to standard alternators, which provide a constant supply of power to both battery and electrics. A smart alternator can choose when to charge the battery. For example, on acceleration, a smart alternator can stop recharging the battery so that the power from the engine is used to support the acceleration. This reduced drain on the engine can lead to improved fuel efficiency. When less engine power is needed, the smart alternator will overcharge, as taking more engine power and converting it to AC/DC power will not impact vehicle performance.

Common car alternator problems

Alternators may not be huge in size, but they do a big job, and have several moving parts. As most people will know, the more moving parts something has, the more chance there is for it to go wrong. The most common problems with an alternator are loose or worn drive belts, connector faults and worn bearings. Repair costs will depend largely on labour charges, which will be dictated by the make of your vehicle and the location of your alternator.

Your mechanic should be able to advise you of the rough cost of repairing or replacing your alternator based on your vehicle make. To find out more about signs that your alternator is not functioning properly, follow us on X or Facebook for next week’s blog.

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