A car’s battery is a device that stores energy and work on the mechanism of converting chemical energy (produced by chemical reactions) into electrical energy. The stored electricity stored used to start the motor initially, then to promote ignition and then to initiate the fuel system of the car. Once the car is started completely, the battery begins charging.

It’s very important for a car’s owner to test his car’s battery and electric system frequently. Take precautions before it gets weak. Because a weak battery is of no use.

In this article, you will come across all the processes through which you can read the voltage of your battery in detail. I hope you find it useful in every way.

No. of volts a car’s battery should have when it is charged:

A complete car battery should have a capacity of 12.7 volts, while that of the functioning engine should be 13.7 – 14.7 volts. If you lack the multimeter (a device used to measure voltage) you can test the voltage of your car’s battery by the following ways:

Headlights voltage testing:

You can check the voltage of the car’s battery by starting the car and turning on the headlights. If they produce dim lights, it illustrates the lights are running off the car’s battery, which hints that there is no charge formed by the alternator. If the lights shine brighter, it explains that alternator is producing some current. If they produce normal light, whose intensity does not change then it indicates normal functioning of the battery.

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Open Circuit Voltage Testing:

Open circuit voltage test pin down how fully the car’s battery is charged. This is done after 12 hours of shutting your car down to fritter away if any surface charge was left. Open circuit voltage testing requires switched off engine to avoid any sort of emergency or accident.

Then the multimeter or voltmeter is used to measure the voltage up to 20 (twenty) volts. Leads are then connected to the battery terminals with respect to their polarities, positive lead to the positive terminal and negative lead to negative terminal respectively to calculate the voltage.

Voltmeter readings and their Indications:

12.65 to 12.77 volts = your battery is fully charged.

12.45 to 12.54 volts = your battery has a 75% charge.

12.24 to 12.29 volts= your battery is 50% charged.

11.99 to 12.06 volts= your battery has 25% charge.

11.75 to 11.89 volts=your battery is dead.

Electrolyte Gravity Voltage Testing:

The electrolyte gravity method is another kind of voltage checking technique of a car’s battery and is used for non-fixed “Lead Acid Batteries”. In this method, a “Hydrometer” is used to measure the voltage of the car’s battery.

Values of Specific Gravities and their Indications:

1.269 = your battery is completely charged.

1.229= your battery has a 75 % charge.

1.194= your battery is 50% charged.

1.159= your battery has a 25% charge.

1.124= your battery is completely dead.

Capacity load voltage test:

The capacity load test is to measure the current production of a battery. This test is performed when your battery has charge of at least 75%. The voltage of the battery is calculated under a load similar to how much it requires to start the car.

Then a load tester is used which consists of a large resistor, with resistance equal to the car’s starter and a meter showing the output voltage.

A car’s battery voltage should be checked on a regular basis. If you can’t afford regular checking of the battery, then check it at least once a month especially when the cold weather starts.