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.
> A battery is a combination of two or more cells.
> Cells which cannot be recharged are called **primary cells**. Cells which can be recharged are called **secondary cells**.
Cells and batteries can be connected to each other in electrical ciruits to increase the overall voltage and current that is produced. There are three main connection types:
> The key thing to remember: **cells configured in series increases the overall voltage available** and **cells configured in parallel increases the overall current available**
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.
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):
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.
In parallel connections all positive terminals are connected to each other and all negative terminals are connected to each other.
This time the voltage is the same of each individual cell but the current is the sum of the individual cell currents. So the voltage is constant but the current is accumulative:
If we want both a higher voltage and a higher current we can use series-parallel configurations. Connecting cells in series increases the voltage and connecting cells in parellel increases the current so doint both boosts the amount of both quantities.
