How Do Batteries Work?

There are many different types of batteries around us.

From the lead acid batteries in our car, to be batteries in our torches, to the tiny batteries in our watches, we are daily surrounded by these remarkable energy storage devices.

And that is what they are – devices that contain energy that can be extracted, and in some cases put back.

The lead acid batteries in our car are one of the oldest batteries in existence, and the design is almost 200 years old. The only technology on cars that is older is the glass.

Any battery contains two electrodes – the anode and the cathode. Different reactions occur at each electrode, and the difference in energy of these two processes can be used to do things, like making a torch shine or a car start.

Imagine we had two water tanks, that were connected by a hose, with a tap between them. Suppose that one tank had more water in it than the other. If we opened the tap, the water woule flow from the full tank to the empty tank. This water flowing is now a source of energy that we could use – for example a little paddle wheel that would turn to make electricity (this is how hydroelectric power works).

In this example, when the water levels were the same, the paddle wheel would stop turning, and no more energy may now be extracted from the system.

This is exactly how batteries work – electrons flow from the anode to the cathode – when the energy of the two systems is the same, the electrons stop and the battery is “flat.”

There are many different designs, to serve many different purposes. Tomorrow we’ll start looking at them, starting with the battery in your car.

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