Electronics Questions: How Batteries Work

From flashlights to computers, there are thousands of portable devices that require electrical power. How do the batteries that these devices use work?

From flashlights to computers, there are thousands of portable devices that require electrical power. They get this power from batteries. There are several types of batteries used in these portable devices. The most common use zinc and carbon but others use lithium, lead, or magnesium. New types of batteries are constantly being developed, including rechargeable batteries.

Batteries use a chemical reaction between two metals inside them to create electricity. These two metals chemically react creating an electrical charge for use in the device when demanded. This reaction is called electrolysis. The negative charge collects at one end of the battery and the positive charges collect at the other. The negative charge flows through a circuit when demanded by the load, and back to the positive side of the battery, creating a direct current circuit.

The electricity used in our homes is alternating current (AC) the electrical current that is used in a portable device is direct current (DC). Direct current is current that flows in one direction through a conductive material, usually a wire. The circuit that is usually connected to a battery requires four things: The power source (in this case the battery), the load (i.e. a light in a flashlight), and two wires, one from the negative terminal to the load and one from the positive terminal to the battery.



The parts of a battery include the steel outer casing or jacket, the anode collector, the cathode collector, the positive end cap (anode), the negative end cap (cathode), and the electrolyte.

The anode and cathode collectors are where the negative and positive charges are collected. The positive and negative end caps are where the electrical circuit is attached to the battery. The electrolyte is a non-metallic conductor that carries current between the anode and cathode collectors.

To better understand how a battery works, you can make your own. There are a couple of ways to do this. In the first example you will need a lemon or other citrus fruit, two small wires and two pieces of different types of metal.

Take the two pieces of metal and tape each one to one end of each wire. Stick each piece of metal into the fruit. Touch the other two ends of the wire to your tongue. The tingling you feel is the electrical current. In this example, the two types of metal act as the anode and cathode, the fruit acts as the electrolyte and your tongue acts as the load.

For a little more complex example you will need seven pennies and seven nickels. Stack them alternately with pieces of salt water soaked blotting paper in between each one. Attach a small wire to each end of the stacked coins. Attach the other end of the wires to a small light bulb. When attaching the wires to the light bulb, ensure one wire is attached to the very bottom of the bulb, and the other wire is attached to the side of the bulb, usually where the threads to screw the bulb into a socket are at. The light should illuminate. In this example, the saltwater acts as the electrolyte and the coins act as the anode and cathode.

When the chemicals inside a battery are depleted, the battery is said to be "dead". In this case, the battery now has to be discarded. Other batteries are "rechargeable". To recharge a battery, the chemical reaction is reversed so the battery can be used again. Most rechargeable batteries can be recharged again and again, saving valuable resources.

Batteries are a very important, if not a critical part of our lives. There are hundreds of portable devices that we use in our modern lives. Cell phones, computers, and MP3 players may come immediately to mind, hearing aids, pace makers, and even your car may not. All of these devices and hundreds more that we take for granted everyday require batteries, some rechargeable, but not all. Having a better understanding of how they work and conserving their energy will help you get the most out of them.

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