While the specific design of EV batteries may vary with manufacturer the basic building blocks are similar in design and all based around a relatively simple electrochemical cell. Several cells, each in its own package are assembled together inside individual carrier modules, multiple modules are then connected together to form a battery pack. In order for this battery pack to function properly and to operate at optimum available charge it is essential that the temperature of the pack is closely maintained and controlled. This poses quite a technological problem for the automotive makers and suppliers as the technology required is fairly advanced.