9.7.4 Immediately after this overch

9.7.4 Immediately after this overcharge period, the battery shall be weighed under the same conditions as in 9.7.1 with the same scales (W2). 9.7.5 The ratio (W1-W2)/Cn shall be calculated and compared against the requirements listed in Clause 10. 9.8 Vibration resistance test 9.8.1 After charging according to 8.2, the battery shall be stored for 24 h at a temperature of 25 °C ± 2 °C. 9.8.2 The battery shall be fastened rigidly to the table of the vibration tester. The fastening shall be of the same type as that used on a vehicle and secured by either – the bottom hold-downs or ledges on the lower part of the container and suitable hold-down clamps and bolts with M8 thread, tightened to a torque of between 15 Nm and 25 Nm, or – an angle-iron frame covering the upper edges of the battery case/cover assembly for a minimum width of X mm (see table 5), connected to the vibration table by four screwed rods with M8 thread, tightened to a torque of between 8 Nm and 12 Nm. 9.8.3 The battery shall be subjected for a period of T (h) (see table 6) to a vertical vibration of a frequency of 30 Hz ± 2 Hz, these vibrations being as nearly sinusoidal as possible. The maximum acceleration on the battery shall reach the value Z (see table 6). NOTE The battery temperature throughout the vibration shall be between 20 ºC and 30 ºC. 9.8.4 After a maximum of 4 h after the end of the vibration, the battery shall be subjected, without recharge, to a discharge at a temperature of 25 °C ± 2 °C with a current I=Icc. The terminal voltage after 30s (U30s) discharge shall be recorded. The discharge shall then be terminated.