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Your vehicle’s voltage regulator may be available on its own or assembled and packaged together with a new or rebuilt alternator. Either way, it plays a very important role in your vehicle’s charging and electrical systems.



What is a Voltage Regulator?

After alternating current is converted to direct current inside of the alternator, the voltage regulator ensures the proper amount of electricity makes its way to your vehicle’s battery.

The charging voltage should never exceed 14.5V. If the charging voltage exceeds this number, the voltage regulator circuit is likely to be the source of the problem.

How do Voltage Regulators Work?

The voltage regulator is like a kink in a hose. When voltage rises over 14.5V, the regulator “clamps down” on the charging circuit. This electronic clamp prevents the battery from overcharging by limiting the voltage it receives from the alternator.

Limiting the charging system’s voltage ensures your battery stays healthy and works properly, along with the rest of your vehicle’s electrical circuits. When the voltage regulator fails, batteries become overcharged and fuses pop to protect their circuits.

How are Voltage Regulators Made?

Voltage regulators are mass-produced using heavy factory equipment. Soldering is often required to finish the part. After automatic voltage regulators are produced, they are assembled with other parts to form an alternator. Malfunctioning voltage regulators should almost always be replaced with factory or aftermarket parts.

Why do Voltage Regulators Fail?

  • Electrical components, including voltage regulators, are vulnerable to age, heat, and moisture.
  • Vibration over time during normal operation may cause soldered electrical joints to work loose, especially if these joints were poorly executed at the factory.
  • Shorts in the electrical system may cause voltage regulator failure.

What are the Symptoms of Voltage Regulator Failure?

  • Battery swells up due to overcharging. You may hear gases escaping from the battery. These gases are extremely flammable, and you shouldn’t go anywhere near them with an open flame.
  • Your check engine light may come on and stay on.
  • If your vehicle is equipped with a voltmeter on its dash, it may read too low or too high if there’s a fault in the charging system.
  • Your headlamps, tail lamps, or interior lamps may burn out because receiving too much voltage.

What are the Implications of Voltage Regulator Failure?

  • Flammable gases escaping from an overcharged battery may ignite, starting a fire in your engine bay.
  • You may need to replace your battery, depending on its age and whether it has been over or undercharged.

If you have questions or concerns about voltage regulators or any of your vehicle’s charging components, come into your local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.