The Baghdad Battery, sometimes referred to as the Parthian Battery, is the common name for a Baghdad Batterynumber of artifacts created in Mesopotamia, during the dynasties of Parthian or Sassanid period (the early centuries AD), and probably discovered in 1936 in the village of Khuyut Rabbou’a, near Baghdad, Iraq. These artifacts came to wider attention in 1938 when Wilhelm König, the German director of the National Museum of Iraq, found the objects in the museum’s collections. In 1940, König published a paper speculating that they may have been galvanic cells, perhaps used for electroplating gold onto silver objects. Though far from settled, this interpretation continues to be considered as at least a hypothetical possibility. If correct, the artifacts would predate Alessandro Volta’s 1800 invention of the electrochemical cell by more than a millennium.
The artifacts consist of terracotta pots approximately 130 mm (5 in) tall (with a one-and-a-half-inch Baghdad Batterymouth) containing a copper cylinder made of a rolled-up copper sheet, which houses a single iron or (galvanized nail) rod. At the top, the iron rod is isolated from the copper by bitumen plugs or stoppers, and both rod and cylinder fit snugly inside the opening of the jar, which bulges outward toward the middle. The copper cylinder is not watertight, so if the jar were filled with a liquid, this would surround the iron rod as well. The artifact had been exposed to the weather and had suffered corrosion, although mild given the presence of an electrochemical couple. This has led some to believe that wine, lemon juice, grape juice, or vinegar was used as an acidic electrolyte solution to generate an electric current from the difference between the electrochemical potentials of the copper and iron electrodes.
König thought the objects might date to the Parthian period (between 250 BC and AD 224). However, according to St John Simpson of the Near Eastern department of the British Museum, their original excavation and context were not well-recorded, so evidence for this date range is very weak. Furthermore, the style of the pottery is Sassanid (224-640).
Most of the components of the objects are not particularly amenable to advanced dating methods. The ceramic pots could be analysed by thermoluminescence dating, but this has not yet been done; in any case, it would only date the firing of the pots, which is not necessarily the same as when the complete artifact was assembled. Another possibility would be ion diffusion analysis, which could indicate how long the objects were buried.