Easy Ways To Check Your Auto Battery Voltage

using a multimeter to test your automobile battery voltage.

Having a vehicle that won’t start because of a discharged or dead car battery is very frustrating, especially if you don’t have any clue about it. One way of avoiding this to happen is by checking the voltage of your car battery. This can be done by either doing it yourself or by bringing your car battery to a professional mechanic.

If you don’t have any idea about this process, this article will provide you a complete overview of how to check the voltage of your battery. It will guide you through the process to and help you determine what is the voltage of car battery.

Regularly checking your car battery and your vehicle’s entire electrical system is very important. Doing this not just because you are starting to see signs of failure, but as preemptive maintenance will greatly reduce the risk of battery failure.

It will also give you an idea if your car battery needs to be reconditioned or be replaced. To help you check the voltage, here is a complete overview of how to check the voltage of an automotive battery.

What Is The Actual Voltage Of A Fully Charged Vehicle  Battery?

Automotive batteries should have 12.6 volts or above when they are fully charged. And when the vehicle’s engine is running, it should measure in the range of 13.7 volts to 14.7 volts. This can be measured by using a multimeter or by simply doing an electrical test.

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You can do this by turning on your headlights and observe. If your headlights appear to be dim, then they are probably running off the battery. This means that the alternator is producing little charge or no charge at all.

If your headlights get brighter as you rev your engine, your alternator in producing power but not enough to keep the battery charged. If the lights are in the normal state and not changing as you rev the engine, then they are running normally.

2 Ways Of Checking The Voltage

Woman is checking the voltage of her batteryThere are two ways on how to check the voltage of a car battery. Both of these methods are very accurate and will provide you with a reliable result. Either of these two is used by mechanics and car experts to determine the voltage of car batteries. To learn about these methods, just continue reading below.

Open Circuit Voltage Check

This is a test that determines if the car battery is fully charged or how much it is charged. It is done twelve hours after the car is shut off, to allow all the surface charge within the battery to dissipate. By doing so, the test will lead to more accurate reading and reliable result.

This test is done by using a voltmeter or a dedicated battery tester which is connected to the battery terminals. The device which is designed to test batteries will then start to read how much voltage does the battery holds. If a multimeter is used, it has to be configured to read voltage up to 20 volts. Then the leads are connected to the battery terminals.

For results, 12.65 – 12.77 volts reading will tell that the battery is fully charged. If the reading is between 12.45 and 12.54 volts, it means that battery is 75% charged. For the reading that is between 11.99 and 12.06 volts, it means that it 25% charged and if the reading is between 11.75 and 11.89 volts, that means the battery is dead.

Electrolyte Gravity Test

Electrolyte gravity voltage test is a method used for non-sealed lead-acid car batteries. In this method, a hydrometer is used for measuring the battery voltage. This test base it’s reading by measuring the specific gravity of the battery.

・If it reads 1.269, this means that the battery is fully charged.
・If the reading indicates 1.229, then it means that the battery 75% charged.
・If the reading is 1.194 the battery is 50% charged if the specific gravity is equal to 1.159, the battery is 25% charged, and if it indicates 1.124, the battery is dead.

Those are two methods on how to measure the voltage of a car battery. Both of them are widely used and both of them proven and tested methods that provide an accurate result. You can also perform a test that will measure the battery’s capacity to produce current.

To learn this method, you can refer below!

How To Execute A Performance And Capacity Load Test

To measure the ability of the battery to produce current, a performance and capacity load test is needed. Before this test is done, the car battery should have at least 75% charged.

Then the voltage of the battery is measured based on the load similar to the amount of power needed to ignite the spark plug and start the engine. A dedicated load tester is used measure the output voltage. The reading on this test must not be lower than 9.1 volts.

The same procedure is done to measure the cold cranking amps of the battery to see if the battery is capable of starting the car in a situation that the temperature is low.


There you go! Your complete overview and guide on how to determine what voltage is your automotive battery. This article provided you with a complete guide on how each is done and the instrument used for executing them. Keep in mind that regularly checking the voltage of your battery will greatly reduce the risk of battery failure.

It will also let you know if your battery needs to be replaced or reconditioned. Through battery testing, you can avoid the incidents of having a vehicle that won’t start because of dead or discharged battery.

So make it a habit to check your battery once in a while. You can also do the simple test by observing the headlights, to see if your battery is charging properly.

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