a. The battery shall be charged according to the charging procedure specified by the manufacturer: the maximum charging current shall be charged to the maximum charging voltage, and the cut-off current shall be 0.05c ;
b. Disassemble the battery and place small nickel pieces; (disassemble the single cell at the temperature of 20 ° C + 5 ° C and the dew point is lower than - 25 ° C;
C. Wrap the battery back and bring the battery to the test temperature; (place at the upper (lower) test temperature plus 5 ° C for (45 + 15) min respectively)；
d. Pressure step. (the pressing step is required to be completed within 10min, and the pressure is required to be applied at the speed of 0.1mm/s to the part where the small nickel sheet is placed on the single cell. At the same time, use the voltmeter to monitor the change of the voltage at the output end of the single cell. When a voltage drop greater than 50mV is observed, or when the applied pressure meets the requirements (cylindrical battery 800N, square battery 400N, and there is a slight difference between square and cylindrical extrusion methods), stop reducing the pressure I tool and keep it for 30s, Then remove the pressure.)
Result: no fire. If there is no fire, record the pressure in case of internal short circuit.