OVER-CURRENT PROTECTION DEVICE OF SECONDARY BATTERY, PROTECTION METHOD THEREOF, AND BATTERY PACK THEREOF

An over-current protection device of a secondary battery includes a main relay, an auxiliary relay connected in parallel with the main relay, a current limiting resistor connected in series with the auxiliary relay and a controller for detecting an over-current and protect the battery module. The controller turns on the main relay and turns off the auxiliary relay in a normal state where the battery module is recharged by the generator. When the over-current is detected, the controller turns on the auxiliary relay and turn off the main relay so that a limited current flows through the current limiting resistor.