A small number of rechargeable Nikon batteries have experienced problems, prompting the company to issue a recall notice.
Users of the D800, D800E, D7000, V1 take note — Nikon has issued a limited recall of some of your batteries due to electrical issues. This is the EN-EL15 battery, and Nikon has reported seven cases worldwide of a short circuit causing the battery to overheat and deform. No injuries have been reported, but warped batteries can be dangerous.
Here's how to tell if your battery is being recalled:
To determine whether a battery pack is in lots E and F and among those being recalled, first confirm that “EN-EL15” is written on the name plate on side of the battery pack, as shown on the photo below. Then on this same side of the battery pack, locate the lot number for your EN-EL15 battery pack. Lot numbers are alphanumeric characters printed in blank ink at the bottom of this name plate as shown in the photo below. Tilt the battery pack so that light shines directly on the area to see the lot number. If you have an EN-EL15 battery pack with the 9th digit of the 14 digit lot number with either the letter E or F, you should immediately stop using it and remove the battery pack from the battery compartment. EN-EL15 battery packs with which the 9th digit is an A, B, C, D, G or any subsequent letter in the alphabet are not affected and not subject to this recall.
If your battery is a recalled on, immediately stop using it, and contact Nikon at the link above. They'll send you a new one, and take the old one off your hands.