Abstract: An energy storage system comprising at least one energy storage module adapted to supply electrical energy to a hybrid vehicle. The energy storage module comprises an enclosure and at least one battery array located within the enclosure. The battery array also includes a voltage sense board having a plurality of bus bars disposed therein. The bus bars connect a positive terminal of a first battery cell to a negative terminal of a second battery cell. The voltage sense board has missing final bus bars in designated locations of the voltage sense board to limit the exposed voltage to 50 volts during initial assembly. The final bus bars are installed last in conjunction with safety covers which have overlap portions to cover the installed final bus bars.