Unexplained mysteries · Mesopotamia · Parthian or Sasanian period

The Baghdad Battery Hypothesis

Contested150 BCE – 650 CENear Baghdad, Iraq

Clay jars with copper and iron inside — an ancient battery, or something far more ordinary?

Research draft · editor review pending. Every claim below is linked to a checked source, but this dossier has not yet been reviewed by a human editor. Spot an error? Corrections are logged.

In the 1930s, a set of ceramic jars from the region around Baghdad drew attention because some contained a copper cylinder and an iron rod. If filled with an acidic liquid, such an arrangement can produce a small voltage, and the idea of an ancient 'battery' took hold.

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How to read the labels

EstablishedSupported by strong, converging evidence.

ContestedEvidence exists but qualified scholars disagree.

UnresolvedThe question is open; evidence does not settle it.

LegendComes from myth, literature or tradition, not physical evidence.

SpeculativeA hypothesis with little direct evidence so far.

Hero image: Modern replica of the vessel's copper cylinder and iron rod (not the original artifact). Photo: Tympanus · Copyrighted free use · via Wikimedia Commons. Evidence labels describe the written claims, not the image. Version 1 · updated 2026-10-22.