• Dim lights.
• Flickering gauges.

Any one of these symptoms can be a sign of a weak charging system. Your charging system is responsible for restoring the charge to your car battery after use and is tasked with providing power to your lights, audio system, and other electronics while your vehicle is running. Without your charging system in proper working order, you’ll eventually find yourself stranded…without lights…and without good tunes. Gasp.

To help you avoid such a situation, we’ve put together a basic guide to tracking down potential charging system issues.

Problem: Engine starts OK, but the battery does not stay charged.

Solution #1: Focus on your battery first. If your vehicle has stopped running, jumpstart the engine, remove the jumper cables as quickly as possible, and wait. If the vehicle keeps running after a period of time, there’s likely a problem with your battery. Take into account the outward appearance and age of the battery when deciding whether to replace it. Also, inspect your battery cables and make sure they are in good shape. Bad cables will not deliver the full current flow needed to operate properly.

Solution #2: If the battery won’t hold its charge and your engine stalls out, then it’s time to turn your attention to the alternator. Although your battery may have enough energy to get the engine fired up initially, it will eventually lose power if it is not being recharged by the alternator. Here are a few quick ways to pinpoint a bad alternator:

1. Crank over the engine, turn on your vehicle’s lights, and observe. If they start bright and then slowly fade, your alternator might not be delivering the proper charge to operate your vehicle accessories.
2. If your vehicle is already dead, jumpstart the battery and wait. If the alternator is bad, your car or truck will eventually die out again as the battery is not re-charged.
3. Get a good-quality voltmeter or multimeter and test your battery’s state of charge. The voltmeter should read around 12.6 volts with the engine off and 14-15 volts when the engine is running. If voltage is below 13.5, there’s a good chance the alternator is not keeping up with your battery’s charging needs.

Solution #3: Check the alternator cables for abnormal wear, including cracking and fraying. Replace or tighten the cables as necessary.

Problem: Engine cranks over slowly and lights dim excessively during process.

Solution: Slow or labored cranking is often the first sign of an undercharged battery. Use the tests above to determine the problem—battery or alternator.

Problem: Lights flare excessively as engine speed increases.

Solution: This is usually caused by an overcharged battery, which is typically the result of high alternator voltage. This can be caused by a short or ground in the rotor field winding within the alternator or a defective regulator.

Problem: Dim lights or lights that seem to fade as the car runs.

Solution #1: Since the alternator is responsible for supplying the auxiliary power to your lights and electrical components, start with the alternator and associated items. First, examine the wiring for damage or wear and replace as necessary. If everything looks good, move on to solution #2.

Solution #2: Turn on your vehicle and use a voltmeter to test your battery’s charge. If voltage is below 13.5, there’s a good chance the alternator is not keeping up with your battery’s charging needs and will need replaced. If voltage is around 13.5-15, turn your attention to your battery.

Solution #3: If the alternator is supplying proper voltage, chances are the problem lies with your battery.