A power pack system includes an energy storage system having a plurality of energy storage devices and a thermal management system. The thermal management system includes a battery ventilation system connected to energy storage system for achieving and maintaining a predetermined temperature within energy storage system by providing a two way circulation of a working fluid. Further, the system includes a housing having a top cover and a bottom cover to receive and secure the energy storage devices therein. The top cover and bottom cover configured to retain said energy storage devices in a sealable manner. Further, a method for achieving and maintaining a pre determined temperature within an energy storage system includes providing two way circulation of a working fluid and maintaining a uniform flow velocity of the fluid at least inside the energy storage system.