Nikon Z9 Mirrorless Camera - Manual (Page 850)

850 Compatible Accessories
Calibrating Batteries
The MH-33 battery charger can detect whether batteries require
calibration and calibrate them as necessary to ensure the accuracy of
the battery level display.
Calibration status and progress are shown by lamps on the battery
charger:
If the calibration lamp flashes when a battery is inserted, the battery
needs to be calibrated.
CHARGE %
CALIBRATION
6h
4h
2h
100
80
50
1
2
3
1 Charge lamps
2 Calibration lamp
3 Calibration button