The Penny Battery is a form of wet cell, based on the Voltaic pile. It is often used as a more advanced experiment to build upon the concept of an Electrochemical cell, the simpler example being the Lemon battery experiment.

[edit] Design

The penny battery design consists of Canadian pennies from 1997-1999 as the zinc electrode and 1942-1996 pennies as the copper electrode. The 1997-99 Canadian pennies can be replaced by American pennies from 1982-Present, while the 1942-96 Canadian pennies can be replaced with 1944-82 American pennies. Between the pennies are pieces of tissue or cloth soaked in lemon juice. One cell, that is one copper penny, one zinc core penny (copper coating having been removed from one side), and one layer of tissue soaked in lemon juice, will produce 0.8 V when the tissue has been recently moistened. When the tissue had been given a chance to dry, or the lemon juice has leaked out, the voltage may drop to 0.5-0.3 V. Multiple cells can be stacked one on top of the other to form a battery. For practical purposes, wax paper or cellophane is sometimes used to keep moisture out and to keep the lemon juice in. The wrap also helps to keep the cells in line. Penny and nickle rolls can be used to keep the cells in line, and also to ensure that the sides of the individual cells are not exposed to potential short circuits.^[1]

[edit] Variations

The penny battery has different variations, which all operate at different levels of effectiveness. The zinc core pennies may be replaced with nickles, or other coinage, as long as they differ enough from the copper pennies. The lemon juice may be replaced with vinegar, or even salt water.^[2]

[edit] References