scope:

Introduction

Secondary cells are those where the chemical reaction that produces electricity can be reversed. This means that when a cell is "run down", it can be re-charged by passing electricity through it in the opposite direction. This, in effect, stores up another supply of electricity in the cell and it is ready to be used again as a power source. The discharging and re-charging can be done many times.

Each cell produces between one and a quarter and two and a half volts (according to the type of cell). Cells can be connected together to produce the required total battery voltage. Sometimes the manufacturer makes them in groups of cells already connected up in a box or crate.

The electrodes of secondary cells are commonly referred to as plates, as this is often their shape.