How To Diagnose A Failing Alternator
A failing alternator is a common issue, since alternators last about 100K-150K miles. It can be quite difficult to identify a failing alternator, though. If you think your alternator may be failing, diagnose this part and then replace it ASAP if necessary. The alternator is such an integral part of your vehicle that your car cannot function without it.
Why Is The Alternator Important?
The alternator is responsible for converting chemical energy to electrical energy. In doing so, the alternator keeps the battery charged. Think of this as a generator. When your car’s wheels spin, the serpentine belt powers the alternator. As long as the alternator is being powered, it produces enough electricity to charge your battery.
How To Tell If Your Alternator Is Failing
An alternator should last between 7 and 10 years in ideal conditions. It's quite possible for it to fail early, though. Whether you're driving with a new alternator or one that's nearing the end of its life, it's good to know how to detect the signs of a failing alternator. Here are the most common tell-tale signs of a failing alternator:
- Battery dying quickly: The alternator’s job is to charge the battery. So if your battery is consistently dying and needing a charge, this could be due to a failing alternator.
- Trouble starting and frequent stalling: An alternator’s failure to charge a battery can lead to your vehicle having difficulty starting. It may even stall out when idling.
- Dim interior and exterior lights: Do your headlights, dashboard lights, and radio lights appear dim in unison? This could be another sign that your alternator is no longer charging your battery.
- Warning lights: The dash may display a battery symbol or say “GEN” or “ALT” to warn you of a failing alternator.
- Burning rubber smell: A worn out or overworked alternator can emit the smell of burning rubber. This is caused by either damaged wires or the wires overheating from trying to push too much electricity out.
- Whining noise: Damaged or worn out alternators commonly emit high pitched whining noises when running. These noises often get louder as the vehicle accelerates.
How To Diagnose A Failing Alternator
If you observe any of these signs in your vehicle, you can perform a test to see if your alternator is worn. The issue may be either the battery or the alternator. The steps laid out below will help you determine which part is failing. You would need either a voltmeter or a multimeter.
- Make sure that your engine is off.
- Attach the voltmeter or multimeter to the battery. Attach the voltmeter’s red lead to the positive terminal and the voltmeter’s black lead to the negative terminal.
- Read the voltmeter. If the reading is over 12.2 volts, the battery has enough power to start the alternator. If it’s under 12.2 volts, the battery is likely bad.
- Grab a buddy and then have them watch the voltmeter.
- Start the engine and then rev it to 2,000 RPM. See if the voltmeter shows a higher reading as you rev the engine.
- It should read at least 13 volts. If you change the RPM and if the reading fluctuates, the alternator is working fine.
- If the reading doesn’t change, then the alternator is likely bad.
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