When it comes to pricing energy from batteries it is difficult just to try and quote cost/kWh. There is obviously a very wide range of battery sizes in terms of both electrical capability (voltage, current and energy) and physical values (size and weight), as well as various materials used to make them with the range of applications and needs equally large.
In a short discussion it would be impossible to try and cover all aspects but for many applications some idea of the cost of using batteries could be useful.
With special applications such as watches, hearing aids, pocket calculators and electronic dictionary type units and other applications requiring physically very small power sources the size and weight dominate and while there are a very large selection of shapes and sizes made, for the user there is less choice of battery type. Also some of these more special purpose batteries offer voltages other than the very common 1.5V or 9V. However many common pieces of equipment use three main sizes of battery, namely AA, AAA and PP3 as shown together with some of their alternative reference numbers and these three will be discussed further.