Nikon D810 User Manual page 481

• Continuing to charge the battery after it is fully charged can impair
battery performance.
• 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 EN-EL15 battery.
• The supplied power cable and AC wall adapter are for use with the
MH-25a only. Use the charger with compatible batteries only. Unplug
when not in use.
• Charge the battery before use. When taking photographs on
important occasions, ready a spare battery and keep it fully charged.
Depending on your location, it may be difficult to purchase
replacement batteries on short notice. Note that on cold days, the
capacity of batteries tends to decrease. Be sure the battery is fully
charged before taking photographs outside in cold weather. Keep a
spare battery in a warm place and exchange the two as necessary.
Once warmed, a cold battery may recover some of its charge.
• Used batteries are a valuable resource; recycle in accord with local
regulations.
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