Ancient Clay Jar Might Be a Battery. Or a Prayer Box. Possibly Both.

A 2,000-year-old clay jar found near Baghdad contains a copper vessel and an iron rod — the same basic architecture as a modern battery. A new reconstruction study says it may have produced more voltage than anyone thought. Archaeologists who've spent years studying it say it was probably never a battery at all.

Unearthed in 1936 during excavations outside Baghdad, the object — also known as the Parthian galvanic cell — is thought to date somewhere between the 1st and 3rd centuries. The fragments were housed in a museum in Iraq until 2003, when they were lost following the U.S.-led invasion. Everything researchers know now, they're working from records and reconstructions.

Independent researcher Alexander Bazes built one. He argues the unglazed clay jar acted as a porous separator between an alkaline electrolyte and ambient air, creating an outer cell that, when connected in series with the inner copper-and-iron cell, could have produced over 1.4 volts — far more than the roughly 0.5 volts achieved by earlier reconstructions. That's in AA battery territory. Bazes's theory is that the device was built to "ritually corrode" a prayer — paper wrapped around the iron rod, the corrosion itself serving as physical proof that something had happened.

University of Pennsylvania archaeologist William Hafford isn't buying either version. He argues the battery theory isn't persuasive, and that similar finds in the region — including one clay jar containing 10 nested copper vessels — suggest these were magical devices that once held a prayer or curse inscribed on paper. A significant issue critics raise is the complete absence of any archaeological evidence for wires or other components necessary to draw power from the jars.

The artifact is gone, lost in the chaos of 2003. The jar may have been a battery. It may have been a prayer box. At this point, the only thing everyone agrees on is that someone, roughly 1,800 years ago, put copper and iron inside a clay pot and sealed it up tight — and we still have no idea why.

Read the full story at Chemistry World, January 23, 2026

Hot Take: The most telling detail in this whole story isn't the voltage — it's that the artifact is lost, swallowed up in the chaos of 2003, and now we're left reconstructing a reconstruction. History has a way of doing that to the things that matter most.