NOVELTY - The cooling jacket (106) has a primary half section and a secondary half section. The primary half section and secondary half section are identical and flip-ably connected to each other. A channel is provided in between the primary half section and the secondary half section. A coolant flows in the channel provided between the primary half section and the secondary half section. The two half sections are injection molded halves and are made of plastic.    USE - Cooling jacket for battery pack (claimed) for retaining several energy storage cells. Can also be used in internal combustion engine such as diesel engine, gasoline engine or natural gas engine, electrical vehicle, hybrid vehicle, excavator, articulated truck, locomotive, off-site generator, and for use in power grid stabilization in solar plant, hydro plant or nuclear power plant, and used in fields of cell tower and automobiles.    ADVANTAGE - The cooling jacket for the battery pack provides an efficient heat transfer between the energy storage cells to operate at lower temperatures, and provides a structural support for retaining the energy storage cells and increasing the overall efficiency of the battery pack. A single controller is configured to control the overall operations of the battery pack thus reducing the overall space of the housing. The single housing enclosing all components reduces the size and cost of the overall assembly. The compact arrangement including the battery pack and the associated components in the single housing eliminates a need of high voltage connections, and avoids excess weight and material for packaging of the energy storage cells.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a battery pack for retaining several energy storage cells.    DESCRIPTION OF DRAWING(S) - The drawing shows an exploded perspective view of the battery pack.    Battery pack (100)    Cooling jacket (106)    Mechanical fitting (110)    Inlet opening (114)    Outlet opening (116)