NOVELTY - The battery has several interconnected battery cells which are provided with output terminals for outputting the electrical output voltage. A securing device (20) secures the battery cells by separating the battery cells from the output terminals, when fault is occurred in output terminals. The securing device is provided with pyrotechnic switch (24) and thermal trigger element (30) that are arranged separately in a drive circuit (25). The thermal trigger element is thermally coupled to a resistive element (26) which is provided with a heating element.    USE - Battery such as lithium-ion battery used in motor vehicle, hybrid vehicle and electric vehicle (all claimed). Can also be used in automotive and stationary applications.    ADVANTAGE - The securing device is provided for securing several interconnected battery cells by separating interconnected battery cells from output terminals, when fault is occurred in output terminals, hence safe operation of the battery with several battery cells in normal operation can be attained. The robustness against the use of protection can be ensured. The accidental triggering can be avoided. The use of pyrotechnic switch and thermal trigger element can be realized. The safety can be ensured. The detection of the temperature can be performed at suitable position by pyrotechnic switch, hence reliable separation can be attained. The flexibility, reliability and battery safety can be improved. The battery can be protected efficiently from short circuit and over current. The handling of the battery can be ensured in the event of danger. The vehicle protection can be improved.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a method for safe operation of battery; and    (2) motor vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the battery.    Securing unit (20)    Pyrotechnic switch (24)    Drive circuit (25)    Resistive element (26)    Thermal trigger element (30)