How to Check a Car Battery

The battery is the electrical energy storage system of the car. Every electrical accessory and device, used in the car, owes its operation to the power supplied from it. Everything from the ignition system of the car, to the onboard computer in modern cars, is dependent on it.


Automobile batteries are commonly called SLI (start, lighting, ignition) batteries, as they provide electrical power and allow to work ignition system, lights, and the starter of a car. They are (electrochemical) lead-acid type batteries. Most of them are a combination of six galvanic cells connected in series.

Each cell consists of lead plates and lead oxide, immersed in sulfuric acid (at a concentration of 35%). A chemical reaction between the plates and the electrochemical liquid allows the storage of charge and discharge of a battery.

The reversible reaction of lead, lead oxide, and sulfuric acid, the reaction to produce lead sulfate, is responsible for the discharge and recharging of the battery. Each of the six electrochemical cells provides a voltage output of 2.1 V, providing a total voltage power of 12.6 volts. It is essential that dilute sulfuric acid and a certain minimum water level be kept indoors, for efficient charging and discharging into the battery.

The battery is charged by the car’s own dynamo, called an alternator. When the car is moving, the dynamo is driven to produce the load, which is supplied and stored in the battery. If the alternator does not operate properly, the battery will discharge quickly. A low battery voltage level may indicate that something is wrong with the battery or alternator. Thus, when checking an alternator, the output voltage of the battery must be tested.

Verification with a multimeter

Check a Car BatteryThere are two steps to performance monitoring. They consist of checking the output voltage of the battery, when the car is not working and when it does not work. Do not smoke when you check, as a safety measure. Wear safety glasses and gloves when testing.

Check the physical state of the battery. Check for cracks in the outer casing. Make sure all battery connections are in order and do not suffer any damage.

The first step requires that you stop the car output voltage and test. Set the digital multimeter wheel to DC volts. Connect the positive test lead to the positive terminal of the battery and the negative lead test is connected to the negative terminal of the battery. If the output voltage is anywhere in the range of 12V to 12.4V, then the battery is in excellent condition. If it is significantly below these values, you must have it checked.

Then start the ignition and put the car in neutral. Let him stay idle for a while. Then, check the output voltage again. If the voltage is in the range of 13.8 V to 14.3 V, the battery works well. If the voltage is below these values, you must check the alternator and the battery.

The majority of the car’s electrical problems stem from alternator malfunction and a dip in charge of the battery. Make sure that you are checking the battery voltage for regular exercise, or you can be left high and dry, with a dead battery.

battery reconditioning

Leave a Comment