In 1930, the Austrian archaeologist Wilhelm König took part in a German expedition to Warka (Iraq), which he later directed. In 1931, he was appointed Assistant Director of the Baghdader Antikenverwaltung (the Baghdad Antiquities’ Administration), becoming its Director in 1934. In 1938, working for the Iraq Museum in Baghdad, he carried out an excavation on a Parthian site at Khujut Rubu‘a, where he found a 15 cm high ceramic vessel. It contained a cylinder of sheet copper soldered with a 60:40 lead/tin alloy, capped with a crimped-in copper disk and sealed with bitumen or asphalt, with a further insulating layer of asphalt on top. This held in place an iron rod suspended in the centre of the cylinder, which showed signs of acid corrosion.

König identified this vessel as an ancient electric battery and experimental copies showed that it was capable of providing a charge of about one volt using lemon juice or vinegar as an electrolyte. As a result, they soon became known as the batteries of Babylon. Other examples were soon identified, all belonging to the Parthian period (from the mid third century BCE to the early third century CE). König suffered a heart attack in February 1939, as a result of which he had to return to Germany.

Some writers have seen in this electric cells evidence for a technologically advanced civilisation in remote antiquity or as evidence for visits by such a civilisation to one more primitive. However, it should be remembered that these artefacts are contemporary with the growth and height of the Roman Empire, hardly a period in which such a civilisation would have gone unrecorded, particularly when the Parthian Empire was Rome’s principal enemy in the east. Furthermore, although König believed that there is evidence for Mesopotamian electroplating of silvered copper vessels, this is no longer thought to be the case, as the items in question are believed to have been fire-gilded, using mercury. There are certainly no remains of electric motors, electronic circuitry or even of batteries capable of generating the greater power needed to drive such devices.

There are alternative explanations that derive from the obvious inefficiencies of the pots to act as galvanic cells. The asphalt seal is a complete seal, so there would be no way of obtaining any electricity generated within the pot; this suggests that containment was an important consideration in their design. Similar objects from Seleucia were used for storing sacred papyri and this is at least as likely an interpretation as the battery hypothesis.

The ‘batteries’ were among objects looted from the Iraqi National Museum in Baghdad during the invasion by the USA and its allies in 2003. It is not known where they are now or if they even still exist.