The Baghdad Battery

These days, batteries are everywhere and in everything. You’ve probably got one in your pocket right now, in fact (in your phone). The origin of modern batteries can be traced back to good ol’ Big Ben Franklin in the 1700s, but the alkaline batteries that were the standard for decades did not appear until 1899. Less than two decades later, lithium batteries had been developed; lithium-ion batteries took another 60 years to appear, with rechargeables not far behind.

But way, way back when, in the Parthian period (circa 250 BCE to 224 CE), the first-ever battery was invented. Or was it?

Scroll Storage or Power Source?

The “Baghdad Battery” consists of three components: a ceramic pot, a copper tube, and an iron rod. Though its true purpose remains unclear, the most widely accepted explanation of this disparate trio is that they were used collectively to store sacred scrolls—wrap the scrolls around the rod, but the rod into the tube, and stow the tube in the pot.

A modern, commercially-available version of the Baghdad Battery.

A modern, commercially-available version of the Baghdad Battery.

However, upon its initial discovery, it was speculated that these three pieces could be combined to create a galvanic cell; that is, a battery.

Some folks speculate that, with the addition of wine, lemon juice, grape juice, or vinegar to serve as acidic electrolyte, the copper and iron materials could function as electrodes and produce an electrical current. Researchers, particularly German painter and naturalist Wilhelm “Big Willie” König, noted that a high number of objects from ancient Iraq (whence the “battery” originated) were plated with very thin layers of gold. These researchers suggest that the Baghdad Battery was used to perform an early type of electroplating.

Debunked

Though at least two attempts to duplicate the Baghdad Battery’s supposed electrical potential have proved successful, the genuine artifact has since been debunked as a possible power source. Firstly, an iron-copper-electrolyte junction produces gas and, along with it, bubbles; these bubbles would create insulation around the electrode; this insulation would increase with ongoing use, making the battery progressively less effective. Secondly, even in a perfect setup, the voltage generated by an iron-copper-electrolyte cell of this size would be far lower than that required for electroplating.

König later determined that the “electroplated” items he had studied were, in fact, fire-gilded with mercury.

Photo credit: Boynton Art Studio via Foter.com / CC BY