Baghdad Battery250 BC and 250 AD, discovered near Baghdad, with a structure similar to that of a modern battery. It also appears that similar batteries can be located around ancient Egypt, where objects with traces of precious metal electroplating have been discovered at different locations.
In 1938, the German archaeologist Wilhelm König reportedly excavated the 130 mm (~5 inch) long clay jar in Khujut Rabu, near Baghdad, Iraq (though some reports say it was found in the collections of the National Museum of Iraq). The jar contained a copper cylinder, in turn covering and protecting an iron rod, isolated from the copper by asphalt. The artifact had been exposed to the weather and had suffered corrosion.
Konig published a paper reporting the mechanism's resemblance to a battery in 1940. Upon publication, König's discovery was discounted by the scientific community and soon disregarded. Such ancient knowledge in the history of electricity bears no known continuous relationship to the development of modern batteries. Its form, though, is nearly identical to the principles that are in use today. After the Second World War, Willard Gray demonstrated current production by a reconstruction of the inferred battery design when filled with grape juice. Subsequent tests found acidic residues in the original, analysed as an electrolytic solution, perhaps vinegar or wine.
Some people regard the Baghdad Battery as an anachronism because of the belief that ancient civilizations did not have electrical power and therefore would not have had a device that operated on the principles of electric power. The practical uses of this battery is uncertain. Some contemporary researchers have renewed interest in interpreting this artifact, and suggested electroplating precious metals as a practical use for early batteries by Baghdad Parthians, who used it to electroplate metallic items. Artifacts from ancient Egyptian sites, similarly resembling batteries, or bearing traces consistent with precious-metal electroplating, may support that.