Large storage battery. 19th-century illustration of a large storage battery (accumulator, right), storing electrical energy from two smaller electrochemical cells (batteries, left). This accumulator consists of a outer glass jar, with rolls of lead sheets inside. It is an example of a lead-acid battery. Electrochemical cells produce electrical power from chemical reactions. This illustration is from 'Physique Populaire' (Emile Desbeaux, 1891).