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Nobody thinks about batteries—until they've run out of juice, of course. But this humble and surprisingly ancient technology has done far more for human civilization than most people realize.

In fact, the modern world as we know it wouldn't exist were it not for batteries and the unique, utterly essential ability to store electrical energy that they provide. Without batteries, there is no such thing as mobile. Phones, computers, bio-medical devices, even the lowly flashlight: every single electronic device on Earth would have to compete for open an wall socket just to turn on.

So let's think about batteries for a minute. Or better yet, explain everything you could possibly want to know about what they are, where they come from, and—most importantly—how to get the most out of them.

A Brief History of Batteries

Baghdad Battery: Bringing Bling to Mesopotamia

  It's like a scene from Raiders of the Lost Ark. In 1936, a number of small, oddly-anointed terracotta pots were discovered in in the ruins of a village near the modern-day town of Khuyut Rabbou'a on the outskirts of Baghdad, Iraq. Clearly from antiquity, their ages dated to either the Parthian era (248 BC - 226 AD) or Sassanid (224-640 AD), but without an obvious use, the curious jars were donated to the National Museum of Iraq. There they sat on a shelf for two years until the museum's German director, Wilhelm König, rediscovered them in the museum's archives around 1938. Upon König's return to the fatherland in 1940 due to illness, he published a speculative paper that the mysterious vessels may have been a lost precursor of the galvanic cell, one perhaps used to electroplate thin layers of gold onto the plated silver pieces he kept finding during excavations.

Each clay jar measured roughly 5.5 inches tall and was outfitted with a small copper tube (constructed from a rolled copper sheet) surrounding an oxidized iron rod but separated by an asphalt plug. Were the vessel to be filled with an acidic or alkaline liquid, say, lemon juice, grape juice, or vinegar, many experts believe that it could well have generated a small but appreciable current (on the range of .8 to 2 volts if replica devices are any indication). Granted, this amount of voltage generally isn't powerful enough for the uses König imagined as the Mythbusters proved. Anthropologists now believe those pieces were fire-plated using mercury and some speculate that the Baghdad Battery(such as Accu PA3820U-1BRS ) could instead have served as a miracle device in ancient religious or healing ceremonies.

"The batteries have always attracted interest as curios," Dr Paul Craddock, a metallurgy expert of the ancient Near East from the British Museum, told the BBC. "They are a one-off. As far as we know, nobody else has found anything like these. They are odd things; they are one of life's enigmas."

Galvanic Cells: Darth Vader to the Modern Battery's Luke

Frog's legs are funny things. Not just good eatins, they exhibit a tendency to flail when exposed to an electrical charge. At least, that's what Luigi Galvani discovered in 1771 as a professor at the University of Bologna. As the legend goes, he was in the process of skinning a frog pinned via copper hooks to a table where he had just previously conducted various static electric experiments. Galvani's assistant picked up a metal scalpel from the table (which, unbeknownst to either man, carried a static electric charge) and accidentally touched an exposed sciatic nerve. With a small spark, the leg twitched and Galvani glimpsed that electric charge could actually transported by ions, not through fluids or the atmosphere as earlier theories posited.

Voltaic Pile: Were Yurtle the Turtle a Galvanic Cell

  Galvani's misconceptions about the origin of electricity in living beings lasted for the rest of his life, believing that "animal electricity" was borne from a muscle within the hip. Alessandro Giuseppe Antonio Volta, professor of experimental physics at the University of Pavia, was one of the first of Galvani's contemporaries to recreate his famous frog experiment and originally held the same views on animal electricity's hip-based origins. But what Volta realized, and Galvani did not, was that the frog leg was both capable of conducting and detecting electricity.

To prove this point, Volta built a a device he dubbed an "artificial electrical organ." Created by alternatively stacking silver and zinc discs separated by brine-soaked cloth, this arrangement created a circuit and would conduct a charge when connected by a wire. As Volta wrote to Sir Joseph Banks, the president of the Royal Society of London, on the 20th of March 1800:

... In this manner I continue coupling a plate of silver with one of zinc, and always in the same order, that is to say, the silver below and the zinc above it, or vice versa, according as I have begun, and interpose between each of those couples a moistened disk. I continue to form, of several of this stories, a column as high as possible without any danger of its falling.

While he had been attempting to mimic a perceived biological function, Volta had actually invented the Voltaic Pile, world's first electric battery(such as Accu PA5013U-1BRS). It also led him to discover Volta's Law of the electrochemical series—the electromagnetic force of a galvanic cell is dependent on the electrical potential difference of the electrodes. This is why stacking nothing but copper or silver discs will not generate a current.

Galvanic cells rely on a pair of half-cells, each with a differing electrode dipped in electrolytic solution to generate a RedOx reaction and, in turn, an electrical charge. Unlike an electrolytic cell that requires electrical input to get started, the galvanic cell's RedOx reaction is spontaneous. That is, it occurs without any outside impetus. As such, galvanic cells were originally found use powering telegraph lines and improved designs are now often found in batteries, pH meters, and fuel cells.

The Voltaic pile didn't just lead to batteries. It's invention directly led to numerous other major scientific discoveries. William Nicholson and his half-brother Anthony Carlisle built their own voltaic pile and passed the current through a trough of water, thereby discovering electrolysis as the H20 decomposed into its constituent elements. Humphry Davy in the UK used his own voltaic pile to demonstrate that Volta's Law was based on a chemical reaction, not just the electrode's difference in potential, as well as further Nicholson's and Carlisle's electrolysis work. William Hyde Wollaston proved that voltaic and static electricity were one and the same. And just two years after its creation, Vasily Petrov was using them to study electrical arcs.

How Many Different Kinds Are There?

Batteries on the whole are divided into two main classes: Primary cells, which are single-use disposables, and secondary cells, those that can be recharged. Primary cells are typically constructed from Alkaline, Zinc, or Lithium-based chemistry. They're relatively cheap to produce and are designed to be thrown away or recycled after dispensing their initial charge, however they are not exactly environmentally-sensitive. Secondary cells, on the other hand, are usually made from Lead-Acid, Nickel, Lithium-ion chemistry and tend to be more expensive up front than primaries. They can be reused over and over though, so are more economical and environmentally-friendly in the long run.

They're not divided simply by their reusability, mind you. Batteries can also be classified by their cell type into four main groups:

• Wet cell: Wet cells are the oldest type of battery(such as Accu Qosmio X500-128 ) and use a liquid electrolyte to transport ions. Some of the ealiest examples were simply open-top glass jars filled with electrolyte solution and a pair of electrodes sunk into it. While eventually replaced by dry cells in most energy storage applications, wet cells are still widely employed as car batteries, in home chemistry sets, and by a variety of public utilities. They can be utilized as either primary or secondary cells.

• Dry cell: Dry cells work like wet cells, except that the electrolyte solution exists in a paste form with just enough moisture to conduct a charge but not enough to go sloshing about when dropped. These cells, developed from the pioneering Leclanche cell, can also be used as either primary or secondary cells and are generally much safer to use than wets.

• Molten salt: You won't find molten salt powering your wristwatch any time soon. These specialized industrial batteries rely on salt, super-heated to the point of liquification, as an electrolyte. As terrifying as driving around with liquid hot magma under your hood, a molten salt battery's energy density is quite high, making it a potential power source for electric vehicles.

 

• Reserve: Reserves are all the battery with none of the electrolyte, which makes them perfect for short-term use after long-term storage. By separating the electrolyte from the rest of the battery assembly, the cell will not self-discharge while on the shelf. These are more commonly found in scientific and military applications than consumer.