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Cells
Batteries and cells come in all different shapes and sizes and there are many different types.

The pictures to the right show three different types of cells. We usually call them batteries but they are actually cells. A battery is when more than one cell is connected together.

Although they all look different, each of the cells shown to the right all produce a voltage of 1.5V.

The larger cells, such a D and C cells, can supply more current and are best suited for high power products such as torches and remote control cars.

The smaller cells, such as AA and AAA cells, are used for less demanding products such as remote controls, mp3 players and clock etc.
D Size
AAA Size
The advantage of the D and C cells is that they have a high capacity and can supply more current and last longer. They are however heavy and large.

The advantage of the AA and AAA cells is that they are much lighter and smaller. They have a lower capacity however and cannot supply high currents for very long.
PP3 9V Batteries
A battery is a collection of cells arranged to produce higher voltages or currents. The diagram to the right shows how six 1.5V AA cells can be connected in series to create a voltage of 9V.
Inside a 9V battery, each layer is a 1.5V cell
PP3 9V Battery
Batteries
A 9V (PP3) battery is a battery because inside it has a number of cells all piled up on top of each other.

Although a 9V battery supplies more voltage than a single AA cell it cannot supply high currents. A battery of six AA cells (as shown above) would produces 9V but has a much greater capacity than a single PP3. The advantage of a PP3 battery is that it is small and light and is useful in low power circuits. For this reason they are used in smoke detectors.
Battery Symbol
Cell Symbol
Lithium Coin Cells
Rechargeable Cells and Batteries
Coin cells are about the same size as a 10 pence coin. They supply a voltage of 3V and are used in situations where a very small power source is required.

They are found in hearing aids and car lock remote controls.
Circuit diagram of the circuit above

Rechargeable cells are available in a wide range of shapes and sizes. They are available in the same sizes as non-rechargeable cells.

 

The advantage of rechargeable batteries is that they can be used and recharged many times.

 

A disadvantage is the voltage produced by rechargeable cells are different to alkaline cells. Where alkaline cells produce a voltage of 1.5V, rechargeable cells only produce 1.2V. Rechargeable PP3 batteries produce only 8.4V instead of the 9V as with alkaline batteries.

Solar Panels

Photovoltaic solar panels convert light directly into electricity. Solar panels are a type of renewable energy source, this means that they produce energy without consuming any fuel such as coal or oil

 

A disadvantage of solar panels however is that they only function in sunlight so they are not much use at night. It is possible to store electricity generated during the day in rechargeable batteries.

Battery Holders