About batteries: the secondary cell

In a voltaic pile electricity is generated by chemical reaction and, once exhausted, the pile cannot be recharged. This is called a primary cell.

In 1803 The German physicist Johann Wilhelm Ritter built a voltaic pile in reverse. The Ritter Pile consisted of copper discs only,also here separated by layers of substance or cardboard soaked in a saline solution. The column of Ritter could store electric energy, but not produce it. That is what we call a secondary cell, storage battery or accumulator. The electricity necessary to charge the Ritter pile, could only be obtained from a primary power source such as a voltaic pile. That made Ritter's ' discovery interesting, but of little practical use.

1854 brought an important development. The German doctor and scientist Joseph Sinsteden placed two lead plates in a container with dilute sulphuric acid. The sulfuric acid reacted with the surface of the plates and formed a layer of lead sulphate. Sinsteden connected the plates to a primary power source and saw a layer of lead oxide forming on one plate and spongy lead on the other. After this charging the battery could be discharged again with a current of no less than 2V, much more than ever was realized by Sinsteden's predecessors Volta and Ritter. During the discharge lead sulphate was formed on both plates just like the first time. so the process could start again. The lead acid battery was born!