The present disclosure is directed to an improved energy storage system. The energy storage system includes an energy storage device having positive and negative terminals, a battery management system configured to monitor and control the energy storage device, and a power connector configured to electrically couple the battery management system with the energy storage device. The power connector includes a housing and positive and negative bus bars, each containing a positive and negative interface pin, respectively. The interface pins are operatively coupled to the positive and negative terminals of the energy storage device to form a power connection. The housing contains separate, opposing side walls defining an open passageway therebetween. Thus, the open passageway provides air cooling across the power connection.