Mobile rack type battery box for UPS system

A mobile rack battery box adapted to an uninterruptible power supply (UPS), comprising:

• two symmetrical cover shells each having an identical horizontal base wall, vertical front wall, vertical back wall, vertical left sidewall and vertical right sidewall, the horizontal base wall having at least one longitudinal inside groove for receiving electric wires;
• wherein the mobile rack battery box is assembled by fastening the two symmetrical cover shells together via screws with the vertical front and back walls and the vertical right and left sidewalls of one of the two cover shells respectively abutting the vertical front and back walls and the vertical right and left sidewalls of the other of the two cover shells to define a holding space for sealing a plurality of battery cells horizontally abutted against one another;
• wherein said cover shells each have an opening in the respective vertical back wall;
• the opening of the vertical back wall of the one of the two cover shells is mounted with a power output socket for output of battery power from said battery cells;
• the opening of the vertical back wall of the other of the two cover shells is blocked with a sealing plate;
• wherein the vertical left and right sidewalls of said cover shells each have a plurality of beveled ribs disposed at an inner side thereof for tight engagement with said battery cells to securely hold said battery cells inside said cover shells;
• wherein the horizontal base wall of each of said cover shells has a plurality of longitudinal ribs and longitudinal grooves alternately arranged in parallel on the outside so that a plurality of assembled mobile rack battery boxes can be arranged in a stack by engaging the longitudinal ribs of the cover shell of one assembled mobile rack battery box into the longitudinal grooves of the cover shell of another assembled mobile rack battery box.