Baghdad Battery
A 2,000-year-old clay jar containing a copper cylinder and iron rod discovered near Baghdad, hypothesized to be an ancient galvanic cell used for electroplating.
OVERVIEW
The Baghdad Battery is a set of three artifacts discovered in 1936 in Khujut Rabu, Iraq, dating to the Parthian or Sassanid period (approximately 250 BCE to 250 CE). Each consists of a clay jar with a copper cylinder sealed by asphalt, containing an iron rod. When filled with an acidic liquid (vinegar), the combination produces approximately 1.1 volts of electricity. The hypothesis that these were ancient batteries used for electroplating was proposed by German archaeologist Wilhelm König. Critics argue the jars were storage containers for scrolls or food. No definitive evidence of electroplating in ancient Mesopotamia has been found. The Baghdad Battery became a focal point for alternative history and ancient technology theorists.
KNOWN FACTS
Replicas filled with vinegar produce measurable electrical current (0.5–1.1 volts)
Copper-silver electroplating is chemically simple and within the technological reach of the period
Sumerian items exist that some claim show evidence of electroplating rather than mercury gilding
The design is remarkably similar to modern voltaic cells
The asphalt sealing suggests the jars were designed to hold liquid
CLAIMS
The artifacts are galvanic cells capable of generating electricity
Ancient Sumerians used electroplating to apply gold to silver surfaces
Multiple batteries could have been connected in series for higher voltage
The technology was lost or suppressed and only rediscovered in modern times
The Baghdad Battery indicates ancient people understood electricity thousands of years before it was 'invented'
EVIDENCE FOR
Replicas filled with vinegar produce measurable electrical current (0.5–1.1 volts)
Copper-silver electroplating is chemically simple and within the technological reach of the period
Sumerian items exist that some claim show evidence of electroplating rather than mercury gilding
The design is remarkably similar to modern voltaic cells
The asphalt sealing suggests the jars were designed to hold liquid
EVIDENCE AGAINST
No known ancient texts describe batteries, electricity, or electroplating
The electroplating claim for Sumerian artifacts has been disputed
Most ancient clay jars served mundane purposes (food, scroll, storage)
The iron rod and copper cylinder could have simply corroded naturally
The artifacts may be unique because they are not batteries but something else entirely
OPEN QUESTIONS
No open questions recorded.
SOURCES
TIMELINE
Estimated creation date of the artifacts
Discovered at Khujut Rabu, near Baghdad
König publishes the battery hypothesis
Debate continues; no consensus reached