How Exactly Do Batteries Work, Anyway?

We take a lot of things for granted in life. Like entering a room, flipping a switch and expecting a light to go on. Or turning a key in the ignition and assuming the car will start.

A few of us could explain the technical details regarding why a light turns on or a car starts in those situations. But most of us couldn’t. We just take it for granted it will happen. 

The same is true with handheld battery-operated devices. We pop a couple of batteries into a flashlight or a TV remote and voila! They work.

But how do batteries make something work that otherwise wouldn’t? That’s what I want to discuss today. For some of you, this might be the first time you’ve read an explanation for it.

One size doesn’t fit all

Before we dive into that, let’s think about the items we use that are dependent upon batteries. Just to remind us how dependent we are on them. 

We already mentioned flashlights and TV remotes, but there are many more. Including cellphones, laptops and quartz watches.

As well as cameras, transistor radios and pocket calculators. Plus pacemakers, hearing aids and wheelchairs. Even cars and trucks need batteries.  

Batteries for these items and others range from very small to large. But they all serve the same function. And that’s making electronics work without the item needing to be plugged into an outlet.

An electrolyte sandwich

What is this compact power plant we refer to as a battery? It’s a self-contained power pack that produces a limited amount of electrical energy.

It slowly converts chemicals packed inside it into electrical energy. That energy is then typically released over a number of weeks, months or even years. 

Inside a battery’s plastic or metal casing is the cell. It consists of three main elements. One of them is a chemical known as an electrolyte. It’s surrounded by two electrodes, also known as electrical terminals. 

On the outside of the casing are two more terminals. They are connected to the inside terminals and are marked either negative or positive.

To charge or not to charge 

The two main types of batteries are primary and secondary. Primary batteries are disposable. They can’t be recharged. Secondary batteries can be recharged many times.

Primary batteries are usually made of zinc carbon, alkaline or lithium. They’re often called dry cells because they contain no liquid. Zinc batteries have been around since Civil War days.

Alkaline batteries store more energy and last longer. Lithium batteries are often smaller and are used for watches and hearing aids.

Secondary batteries can be large, such as what you have in your car. Or small, such as what you have in your cellphone. 

Electrons on the move

What happens when you connect a battery’s two outer terminals into a circuit? The electrolyte starts buzzing with activity.

The chemicals on the inside are then converted into other substances. Ions are formed from materials in the electrodes and take part in chemical reactions with the electrolyte.

In the meantime, electrons are moving from one terminal to the other through the outer circuit.

Whatever the battery is connected to becomes powered up. A flashlight shines, an electric car’s engine starts and a quartz watch begins keeping time.

Potato or lemon battery?

I mentioned earlier that the electrodes (or terminals) are either negative or positive. They have to be made from two different materials. But both have to be electricity conductors.

One of those materials gives up electrons. The other material receives electrons. If both electrodes were made from the same metal, no current would flow.

Just about anything containing electrolytes can be converted into a battery. Even a potato or lemon.

Stick a galvanized nail (coated in zinc) and a copper nail or wire into one of those items. If you connect a voltage meter to both the copper and zinc, it will show a small amount of electric current.

An electronic tug-of-war

So, what’s going on with the two different metals that could possibly produce that current? 

In essence, there’s a tug-of-war happening. Each is trying to pull electrons out from the other. But only one wins.

That electronic flow from the loser to the winner explains how a battery powers a circuit and makes electronics work.

Great moments in battery history

Just for fun, here are seven key dates in battery history.

250 B.C. to 224 A.D. – A battery is allegedly formed near Baghdad, Iraq using iron and copper pieces and a clay jar containing vinegar or citric acids.

1744 – Jurist Ewald Georg von Kleist of Germany invents the Leyden jar. This glass container with metal foil inside and out stores an electrical charge. 

1749 – The term “battery” is first used by Benjamin Franklin. He refers to a number of connected capacitors.

1800 – Physicist Alessandro Volta of Italy invents the first practical battery. It consists of zinc and silver discs separated by cardboard and soaked in saltwater.

1859 – Physician Gaston PlantĂ© of France develops the world’s first rechargeable, lead-acid battery.

1868 – Electrical engineer Georges LeclanchĂ© of France develops the modern zinc-carbon battery.

1949 – Lewis Urry of Canada invents alkaline and lithium batteries. 

We should be thankful to each of these people who led the charge to making batteries a reality. It’s difficult to imagine life without them.

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