How Does A Car Battery Work? Watch And Read, So As To Understand The Electrical Process

how does a car battery workWe often encounter the terms “My battery is dead” or “I need to recharge my battery” when it comes to fixing and maintaining cars. However, do we understand how does a car battery work? By comprehending its functions, we can be confident you won’t take this essential item for granted no more.

To understand your vehicle’s battery, it also pays to understand a bit about electricity. Electrons are negatively charged particles that can carry an electric current. When you hear references to positive and negative ions, you listen to references to electrons’ absence or presence. Electricity, in general, will flow from a positive to a negative terminal and with the help of electrons.

These terminals are hooked up to all the components of your car that require electricity to function, including your windshield wipers, central door locks, and your engine.

Inside each automotive battery are smaller cells, each of which has its own positive and negative terminal. Each cell has eight overlapping metallic plates for each terminal, making a total of 16 per cell. These cells are coated with lead and thoroughly soaked in a 35% sulfuric acid bath.

Sulfuric acid is a strong acid, which ensures the steady flow of electrons and, therefore, conducts electricity. When the battery discharges, the plate coating is present as lead sulphate. When it is being charged, the plate coating is present as the lead oxide.

When You Turn The Ignition On, How Does A Car Battery Work The On-Board Auxiliaries?

When you start up your car, your battery sends out electricity, which allows the acid bath to react to the chemicals in the battery plates. These plates primarily release electrons, which travel from the positive to the negative side of the plate; and then go from one cell to the next.

In the first cell, electrons carry a charge of 2 volts. As they move to the next plate, they accumulate a total load of 4 volts. By the sixth cell, the electrons will travel from the battery and into the car and carry a total of 12 volts.

It is the basis for auto batteries having the label “12 volts”. A 12-volt surge is enough to get your engine started, although more amps may be required from your battery when you have to use your windshield wipers, air conditioning, central locks, or a high-output stereo system. Overcharging a car battery could lead to less water inside the cells since the cathodic reaction causes evaporation.

It could lead to higher sulfuric acid levels in the battery, allowing a highly corrosive “Acid Soup” to develop. Regular battery maintenance must replenish the lost water, preferably distilled, to avoid adding impurities to the electrolyte.


If someone asks you next time, “How does a car battery work?” At least now, you will have an accurate understanding of its importance and functions within your vehicle. It keeps you mobile, comfortable and safe on the road.

We highly recommend a great resource on common frequently asked battery questions. (Opens in new window)

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