Nikon Z9 Mirrorless Camera - Manual (Page 868)

868 Caring for the Camera and Battery: Cautions
Have Fully-Charged Spare Batteries Ready on Cold Days
Partially-charged batteries may not function on cold days. In cold weather,
charge one battery before use and keep another in a warm place, ready to be
exchanged as necessary. Once warmed, cold batteries may recover some of
their charge.
Battery Level
• Turning the camera on or off repeatedly when the battery is fully
discharged will shorten battery life. Batteries that have been fully
discharged must be charged before use.
• A marked drop in the time a fully charged battery retains its charge when
used at room temperature indicates that it requires replacement. Purchase
a new rechargeable battery.
Do Not Attempt to Charge Fully-Charged Batteries
Continuing to charge the battery after it is fully charged can impair battery
performance.
Recycling Used Batteries
Recycle rechargeable batteries in accord with local regulations, being sure to
first insulate the terminals with tape.