Once I disconnect the battery again , the caliberation data is lost. So I did the caliberation and saved the parameter files. After that I disconnect/connect the battery again, it lost the accel and gyro caliberation again, so I saved the parameter files again from QgrounCtrl.
I did the diff command between two parameter files and I got the following data
diff aftercaliberation.params AfterCaliberationAnotherLoss.params
29,30c29,30
< 1 1 CAL_ACC0_ID 1246218 6
< 1 1 CAL_ACC1_ID 1114634 6
1 1 CAL_ACC0_ID 0 6
1 1 CAL_ACC1_ID 0 6
46,48c46,48
< 1 1 CAL_GYRO0_ID 2163722 6
< 1 1 CAL_GYRO1_ID 2228490 6
< 1 1 CAL_GYRO1_XOFF 0.000804828479886055 9
1 1 CAL_GYRO0_ID 0 6
1 1 CAL_GYRO1_ID 0 6
1 1 CAL_GYRO1_XOFF 0.001332331448793411 9
50c50
< 1 1 CAL_GYRO1_YOFF 0.045967467129230499 9
1 1 CAL_GYRO1_YOFF 0.051652405411005020 9
52c52
< 1 1 CAL_GYRO1_ZOFF -0.017645699903368950 9
1 1 CAL_GYRO1_ZOFF -0.017165806144475937 9
61c61
< 1 1 CAL_GYRO_PRIME 2228490 6
1 1 CAL_GYRO_PRIME 2163722 6