Voltage Regulator

What is an Automotive Voltage Regulator and where is it Located?

The voltage regulator controls the amount of voltage being output by the vehicle’s alternator, based on the car or truck’s demand on the electrical system. The voltage regulator ensures that all your of your automobile’s electrical components are running correctly and that the battery is neither overcharging nor undercharging. To do this, it keeps the voltage in the system between about 13.5 and 14.5 volts, as this is sufficient to recharge the vehicle’s battery safely without affecting the electrical circuits and components of the car or truck. When the alternator output gets too high, the regulator stops the flow of electricity from the alternator to the battery to prevent overcharging; when it gets too low, it allows the electricity to flow to the battery again.

Often this is achieved through an electromechanical process. The voltage from the system supplies power to a coil of wire in the regulator. This creates an electromagnetic field that pulls a magnet attached to a switch. Higher voltage pulls the magnet, which pulls the switch to the off position. In lower voltage situations a spring attached to the switch is able to overcome the weaker pull of the magnet and pulls the switch into the on position. In some vehicles a similar effect occurs through more complicated electronic controls. Some vehicles forgo the use of a dedicated voltage regulator and instead regulate the alternator’s output with the vehicle’s computer. 

Prior to the late 1960s – early 1970s, most cars and trucks had a voltage regulator that was separate from the alternator; this type of regulator can be found mounted on to the outside of the alternator or to the firewall or inner fender. While a few models today still do have a separate voltage regulator, the majority of vehicles nowadays have the regulator built internally into the alternator.

How do I Know if my Voltage Regulator Needs to be Replaced?

The electrical connectors and the internal moving parts in the voltage regulator can wear out over time, leading to regulator failure. If the voltage regulator fails, it can result in an output that is too low to charge the battery (undercharging) or too high to safely run the electrical system (overcharging). 

Low voltage may result in your electrical components running poorly. Your headlights or dashboard lights may dim, especially while you are idling. Low voltage will also lead to the battery undercharging because once the alternator is outputting lower voltage than the battery (or not at all), the vehicle will be drawing off the battery instead of the alternator. With a drained battery, you may find that it is hard to start your car or that it won’t charge at all. Even if the car or truck is jumpstarted from another one, it will die once the other vehicle is disconnected, which is not the case with just a dead battery. The starter, of course, relies on power from the battery. Consistent undercharging can shorten the lifespan of the battery. The charging process keeps oxidative products from developing on the battery plates. Undercharging lets this “crust” build up, which makes it harder for the battery to take a charge going forward. 

High voltage can damage electronic components and potentially the battery. Most components can handle up to 16 volts before getting damaged. Above that, and you can have some big issues as any number of electrical modules could burn out as a result, including the engine computer or body control module. If your headlight or dashboard light bulbs receive too much voltage they may burn out as well. If you find yourself replacing light bulbs frequently or unexpectedly, there may be a problem with the voltage regulator. High voltage can also lead to battery overcharging, which is highly dangerous. Battery overcharging can lead to corrosive materials escaping the battery, and potentially even to the battery exploding. A battery that gives off a sulfur smell or makes noise is a sure sign of overcharging and should be avoided.

Can I Replace a Voltage Regulator Myself?

The difficulty of replacing the voltage regulator will vary based on where it is located. It can range from a fairly easy task to one that, while within reach of the do-it-yourselfer, will take a fair bit of effort. If the voltage regulator is mounted to the alternator, you may have to remove the alternator from the engine, and then separate the regulator from the alternator, attach the new one and reinstall the alternator. If the regulator is mounted on the firewall or inner fender, you’ll just have to disconnect the wiring, unbolt it and install the new one in its place. If the regulator is internal to the alternator you’ll have to replace the entire alternator. This is the more likely scenario for most of you reading this. In this case, it is recommended to have the alternator bench tested before replacing. Once the part is removed from the car or truck, any local chain auto part store will have the necessary test equipment, and will usually perform the procedure free of charge. In some cases, a bad power wire or connection in the charging circuit can cause the alternator to not get a proper signal and not charge correctly.

Need a Voltage Regulator Replacement?

By now, you know what can happen if your car or truck’s voltage regulator has failed. The implications are not pretty. As you have probably guessed, if you need a replacement voltage regulator you should get one and have it installed as soon as possible to avoid any disastrous consequences. Here at 1A Auto, we carry a large selection of aftermarket voltage regulators for many makes and models, and at great prices.

We also make shopping for a replacement voltage regulator for your car, truck, SUV, or van easy here at 1A Auto - we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our aftermarket voltage regulators, warranty, compatibility or to purchase, or you can buy online.