A car battery is made of a thick plastic case, lead-based positive and negative internal plates, plate separators, lead terminals and electrolytes. The manufacturing process varies slightly between battery manufacturers, but most are made in similar ways.
Most car batteries begin with a thick case, typically made of polypropylene. The case is divided into six sections. In these sections, things like the negative and positive plates are installed as well as a lead oxide paste. Separators, which are porous insulating materials, are installed to allow the electrical current to flow between the plates. Almost completed, the battery is filled with electrolyte, usually called battery acid, checked for leaks and covered.