An alternator is a generator of electric power in a car and is a major component of the vehicle's charging system. All cars with an internal combustion engine except for some hybrids have an alternator. When an engine is running, the alternator charges the battery and supplies additional electric power for the vehicle electrical systems. It is bolted to the engine and is driven by a serpentine belt (drive belt).
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| An alternator |
An alternator is a maintenance-free unit. It can last for up to 10-15 years without any repairs. If an alternator fails, the car may still run for a short time on battery power (older cars). However, the engine will stall as soon as the battery charge is depleted.
Symptoms of alternator problems
The most common symptom of a problem with your vehicle's charging system is a battery-shaped warning light (in the photo) or the "CHARGE" icon that comes on while driving. Normally this warning light should come on when you turn the ignition, but should disappears as soon as the engine is started. If it stays on, there is a problem with your charging system.
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| Battery warning light |
The charging system warning light doesn't point directly to a failed alternator, although alternator problems are the most common reason. Your electrician will need to do further testing to pinpoint the problem.
Another symptom of a weak charging system is when the dash lights and headlights dim at idle, but become brighter when the engine is revved. This problem could be caused not only by a weak alternator, but also by a failing battery, poor connection at the battery terminals or a loose serpentine belt.
A whining/buzzing noise coming from the alternator is another symptom of alternator troubles. It could be caused by a noisy alternator bearing.
Alternator replacement vs rebuilding
Replacing an alternator costs quite a lot. Another alternative is to have your alternator rebuilt. The way it works is your electrician can remove the alternator and replace the failed components.
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| Old and new alternators |
Whenever the alternator is replaced, it's a good idea to change the serpentine belt too. It is not very expensive, and by replacing it together with the alternator, you can save on labour, as the serpentine belt has to be removed to replace the alternator.
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| An alternator cutaway |
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| A voltage regulator |
The most common alternator problems include worn carbon brushes, worn contact rings and a failed voltage regulator.
Bad outer and inner alternator bearings can produce a whining noise. When the alternator is rebuilt, the bearings, voltage regulator, brushes and some other parts are typically replaced with new ones.
How to make your alternator last longer
Often an alternator fails prematurely when a protective engine undercover or shield is damaged or missing. This happens because water splashing from the road gets inside the alternator and causes it to wear faster. If your engine under-shield is damaged, have it replaced to keep the engine compartment clean and dry. A coolant or oil leak can also damage the alternator.
Similarly, if you have to wash the engine compartment, the alternator must be protected from water and detergent. Personally, I never do this. I have had a terrible personal experience and seen some serious damage result from this.
Twitter and Instagram; @VverteAutoSevcs
Email; vverteautosevcs@gmail.com
Phone; 09137103730
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