How to Test a Car Voltage Regulator

A car’s voltage regulator works hand in hand with two other devices: the alternator and the battery. These devices work by providing adequate power through a car’s electrical system. A properly operational car voltage regulator will ensure that the voltage delivered by the battery and alternator are within the range accepted by the car.

There are two types of car voltage regulators: the grounded voltage regulator, and the grounded field voltage regulator. The grounded type focuses on regulating the negative ground is received by the rotor. On the other hand, the grounded field type regulates positive ground received by the rotor.

Take note that the two actions performed by these regulators affect how much DC the alternator produces. Depending on the type of car voltage regulator being used, the amount of current needed for the battery goes up or down in order to maintain the safety levels of the current. If you want to maintain the functionality of your car voltage regulator, you have to frequently check if it is operating properly. The following are the simple ways on how to test a car voltage regulator.



•Connect the voltage meter to the battery. Using a handheld voltmeter, connect the positive and negative clamps to the contact poles on the car’s battery. Take note that the voltage must have a reading from 12 to 13 volts while the vehicle is running idle. For added safety, use electrician’s gloves or rubber gloves, so you won’t get electrocuted in case you accidentally touch the contacts.

You can also use a multimeter in testing your car’s voltage regulator. Also known as a multitester, a multimeter is an electronic measuring instrument that serves the function of several instruments in one especially when measuring voltage, resistance, and current.

Some auto supply stores also carry an instrument that you can plug into your car’s cigarette lighter or AC adaptor. This instrument will read out the voltage coursing through the car’s electrical system.
•Increase the engine RPM. Ask for assistance to have the engine RPM raised. Ask a friend to gently step on the gas pedal, raising it to 2,000, 3,000 and even 4,000 RPM. This way, the alternator does its job of driving power through the electrical system, and charging the battery (during idling speeds, the battery takes care of the car’s electrical system). The voltage reading should be between 14 to 15 volts.
•Observe the movement of the voltage meter needle. Take note of the voltage meter needle’s movement. If the voltage jumps around or does not go over 12 volts, then your voltage regulator is not working properly.



In essence, the voltage regulator works by means of being a gatekeeper that shuts off the flow of current to the battery whenever the voltage goes beyond a particular level. Through this function, battery overcharging is prevented.

Many models of modern alternators include the voltage regulator as a built-in component. With older vehicles, voltage regulators were very big boxes installed outside of the alternator. When you suspect a busted voltage regulator, you can easily replace this as part of the alternator, or you can have the alternator replaced in its entirety.

  • Issue by:Yael Woods
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