51 lines
2.2 KiB
Markdown
51 lines
2.2 KiB
Markdown
---
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categories:
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- Electronics
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tags: [physics, electricity]
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---
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# Cells and batteries
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Cells are a [voltage source](/Electronics/Physics_of_electricity/Voltage.md#chemicals-cells-and-batteries) that generate a difference of potential via a positive and negative electrode separated by an electrolytic solution. The electrolytes pull free electrons from one of the materials which creates a positive charge. The other material gains the free electrons creating a negative charge.
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> A battery is a combination of two or more cells.
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> Cells which cannot be recharged are called **primary cells**. Cells which can be recharged are called **secondary cells**.
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## Connecting batteries
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Cells and batteries can be connected to each other in electrical ciruits to increase the overall voltage that is produced. There are three main connection types:
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- series
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- parallel
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- series-parallel
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> The key thing to remember: **cells configured in series increases the overall voltage available** and **cells configured in parallel increases the overall current available**
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### Series connections
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With series connections we distinguish **series aiding** and **series opposing** configurations.
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In the case of **series aiding**, cells are connected one in front of another with the positive terminal connecting to the negative terminal of the other in a line.
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In this configuration the same current flows through all the cells, it is not accumulative. We represent this as follows:
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$$
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I_{T} = I_{1} + I_{2} + I_{3}
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$$
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However the voltage is accumulative: it is the _sum_ of the individual cell voltages, represented below as [electrical field](/Electronics/Physics_of_electricity/Voltage.md#distinguishing-voltage-from-electric-field):
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$$
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E_{T} = E_{1} + E_{2} + E_{3} \\
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$$
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// TODO: Add image
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In the case of **series opposing**, negative terminals are connected to each other and positive terminals are connected to each other in a series. This doesn't have many applications.
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### Parallel connections
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Parallel connections follow the series opposing (negative to negative, positive to positive) configuration but they are not connected in sequence.
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_The same current flows through all cells. This is represented mathematically as follows ($T$ stands for time)_:
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