How Do Batteries Work, What are Alkaline Batteries and Rechargeable Batteries?

How Do Batteries Work?

A battery may have just one cell or more than one.
Many flashlight batteries, have only one cell.
Each cell is made up of three main parts.
Do you know how batteries make flashlights and other things work?
When you switch on a flashlight, an electric current flows out of the battery, through the flashlight bulb and back into the battery.
A battery is made of particular metals and chemicals, which produce the electric current. When these metals and chemicals are put together, they make a cell.
Two of the battery parts are solid, and are usually made from a metal such as zinc, or material such as carbon. These two solid parts are called the electrodes.
In many flashlight batteries, one electrode is the zinc case.
This is the negative electrode. 
The other electrode is a carbon rod running down through the middle of the battery.
This is the positive electrode. 
The third part is a chemical liquid or paste, called the electrolyte. This is placed between the two electrodes.
When the battery is connected into a circuit, the current flows out of the battery through the top of the carbon rod, the positive terminal. The current flows back into the battery through the bottom of the battery, the negative terminal.
As the current flows through the battery, the chemicals gradually change. They become weaker and have less energy to make electricity.
Gradually the battery starts to run down.

What are Alkaline Batteries?

Zinc-carbon batteries have many common household uses and usually are the least expensive batteries to buy.
Alkaline batteries are similar in design to zinc-carbon batteries, but their electrolyte material is a different substance. It is able to carry electricity inside the battery for a longer period of time than that in the zinc-carbon battery.
As a result, alkaline batteries last longer and are recommended for electric toys and other items that need heavy current.

What are Rechargeable Batteries?

Have you heard of rechargeable batteries?
These differ in make-up from the zinc-carbon and alkaline batteries.

Rechargeable batteries have what are called reversible chemical reactions. 

When they wear down, a charger device can restore power to the batteries by reversing the discharge of energy that has taken place and making the batteries usable again.
Rechargeable batteries can last for years, and they are often recommended as a way to cut down on having to buy and dispose of too many batteries.
No matter which kind of batteries you use, always handle them carefully. 
Make sure the voltage is correct for what you are using, and have an adult check if you're not sure.