Abstract: The battery pack for electric power tools of this invention has a circuit breaker connected in series with the batteries to protect those batteries from abnormal temperature or abnormal current by cutting-off the current. The circuit breaker is provided with a manual reset mechanism wherein even if the temperature sensing element is cooled, automatic reset will not occur. The circuit breaker must be manually reset. After the circuit breaker detects battery abnormality and cuts-off current, the current cut-off state is maintained until the manual reset mechanism is operated.

Abstract: A battery pack (1) used as a power source for portable units. A plurality of secondary cells (7) are housed in a case (3). One end of the case (3) is formed with a recess (4), in which a plurality of contact terminal plates (10,11,12; 52) are disposed. The contact terminal plates are each bent in L shape as a whole, forming a horizontal portion (30, 53) and a vertical portion (31, 54). The front end of each horizontal portion is formed with a hook (32, 55), which engages an engaging groove (34) formed in the case while a bulge (33) formed on the vertical portion (31) elastically contacts a vertically extending wall (36) formed on the vertical portion, whereby the contact terminal plate is firmly positioned.