When connected in 'series', what happens to the overall voltage of batteries?

When batteries are connected in series, their voltages add together to produce a higher overall voltage output. This is because each battery in the series contributes its own voltage to the circuit. For instance, if you connect two 1.5-volt batteries in series, the total voltage will be 3 volts. This principle is fundamental in electrical circuits since it allows for increasing the voltage to meet the requirements of specific devices or applications.

In contrast, connecting batteries in parallel maintains the same voltage as a single battery, while their capacities increase. The configuration and arrangement of batteries determine how the overall voltage will behave in a circuit, with series connections specifically leading to a cumulative voltage effect.