How do lead acid batteries work?

Lead-acid batteries have changed little since the 1880s, although improvements in materials and manufacturing methods continue to bring improvements in energy density, longevity, and reliability. All lead-acid batteries consist of flat lead plates immersed in a bath of electrolyte. Most types of lead-acid batteries require regular water refills, although low-maintenance types come with excess electrolyte to compensate for water loss during normal life.

A battery consists of Pos. and Neg. plate, the positive plate is covered with lead dioxide paste, and the negative plate is made of sponge lead with an insulating material (AGM or PE separator) in between. The plates are packaged in plastic battery cases and then dipped in an electrolyte solution consisting of water and sulfuric acid.