Battery Pack is a set of any number of identical batteries or individual battery cells. This batteries are configured in a series parallel or a mixture of both to deliver the desired voltage, capacity power density.
A component of battery packs include the individual batteries or cells, and interconnect which provide electrical conductivity between them. Rechargeable battery packs often contain a temperature sensor which the battery charger uses to detect the end of charging. When a pack contains groups of cells in parallel there are differing wiring configurations which take into consideration the electrical balance of the circuit sometimes voltage of batteries need to keep low each individual cell below its maximum value during the charging so as to allow the weaker batteries to become fully charged bringing the whole pack back into balance.