Including a battery is the easiest way that a source of voltage can be provided to an electronic circuit. There are a number of different ways that voltage can be provided, including solar cells (that convert sunlight into voltage) and AC adapters (that can be plugged into a wall). However, for a majority of electronic circuits, batteries are still the most practical voltage source.

Batteries are devices where chemical energy is converted into electrical energy in voltage form. In turn, this can cause the flow of current.

Batteries work by two plates that are made from different metals are immersed into an electrolyte, which is a special chemical solution. The electrolyte and metals react with one another to produce a charge flow that accumulates on the anode, which is the negative plate. The cathode, which is the positive plate, gets sucked dry of its charges. This results in a voltage that forms in between the two plates.

The plates connect to external terminals which can be connected to a circuit that will cause the current to start flowing.

There are many different sizes and shapes of batteries that are available. However, for electronics projects, there are just a couple of standard battery types that you need to be concerned with. All of them are readily available at department, drug, and grocery stores.

There are four standard sizes of cylindrical batteries: D, C, AA, and AAA. There is 1.5 V provided by each battery no matter what size they are. The only difference between the bigger and smaller sizes is that more current is provided by the bigger batteries.

The positive terminal, or cathode, within cylindrical batteries is the end that has a metal bump. The negative terminal or anode is the end that is flat metal.

Rectangular batteries are 9 V batteries. There are six small cells contained inside the small rectangular box that is about half as big as a AAA cell. Each of the small cells produces 1.5 volts and combined create 9 total volts.

When it comes to batteries, there are a couple of other things you need to be aware of.

In addition to 9 V, D, C, AA, and AAA batteries, there are a number of other sizes of batteries that are available. A majority of these batteries are designed for use in special applications, like laptop computers, hearing aids, and digital cameras.

Batteries all contain chemicals that are toxic to both the environment and you. Treat them carefully, and properly dispose of them based on your local laws. Never throw them away in your regular trash.

A multimeter can and should be used to measure the voltage that your batteries produce. The multimeter should be set to 20 V or another DC voltage range that is appropriate. Next, the red test lead should touch the battery’s positive terminal and the test lead should be touching the negative terminal. See here for comms room fit out.

Compared to non-rechargeable batteries, rechargeable batteries are more expensive. However, they last longer, and after they go
dead they can be recharged.

The easiest way that batteries can be used in electronic circuits is by using a battery holder. It is a small plastic gadget that can hold one or multiple batteries.

Do you wonder why D, C, AA, and AAA cells are sold but not B or A? There are actually B and A batteries. However, these sizes never took off.