(10200 - 9181) / 60 = 16.9833333
16.9833333 looks suspiciously like the number of minutes between the two values. Try dividing previousMillis by 1000.
(10200 - 9181) / 60 = 16.9833333
16.9833333 looks suspiciously like the number of minutes between the two values. Try dividing previousMillis by 1000.