The best way to understand a car battery is to break it down into individual components and have a look at how they're made and put together.
What is a battery?
Vehicle batteries are an essential component of many gas/petrol fueled vehicles. They deliver the necessary electricity in order to start an engine. They are made up of a plastic molded container that has both negative and positive lead plating, separators that keep the plates apart, and a solution of electrolytes (water and sulfuric acid).
There are also negative and positive terminals mounted on the top of the container, which are used to connect the engine to the battery.
The Casing and the Cover
The plastic container is molded from plastic. In most cases this plastic is polypropylene. The container has room for six cells. A cell is a well area inside the battery casing. Following completion of molding the cover is left to one side and the other components are installed in the case.
The Battery Plates
Lead (or lead alloy) plates will be fitted into each cell inside the casing. They are used to deliver positive and negative electrodes in order for the battery to produce current.
A lead oxide paste is smeared on the surface of the plates. In the case of negative electrodes certain sulfate compounds are added to the lead oxide paste. Sulfuric acid in a dilute form is then poured into the cells. Finally separators are used to keep the plates from touching and causing a short circuit.
The Battery Elements
If you take a positive plate, a negative plate and a separator together as one unit – it's known as an element. Each element is placed inside the casing and then connected together with a conductor. The terminals of the battery will be connected to the elements.
The Battery Electrolyte
Finally the electrolyte is poured into the casing to completely fill the case. The cover will then be placed on to the top of the case and an engineer will inspect the battery to make sure there are no leaks.