Christofleau galvanic soil battery Every day, millions of people carry a hidden power source in their pockets, unaware that loose change could quietly revolutionize their garden. This video explores the forgotten science of the "Penny Battery"—a simple galvanic cell created by pairing pre-1982 copper pennies with modern zinc-core pennies in the earth. Long before synthetic fertilizers and industrial farming took over, innovators discovered that the soil beneath our feet holds electric secrets capable of boosting harvests naturally.