Nikon D800 Battery
Nikon has announced an important safety issue regarding its EN-EL15 lithium-ion battery as used in the Nikon 1 V1, Nikon D7000, Nikon D800 and Nikon D800E. More information can be found on Nikon's website.
From Nikon: Notice to users of the EN-EL15 Rechargeable Li-ion Battery
This is an important announcement regarding the EN-EL15 battery which is used in the Nikon D7000, D800, D800E and Nikon 1 V1 cameras.
While Nikon takes great measures to assure high quality products, it has come to our attention that a certain number of EN-EL15 batteries manufactured by one of our suppliers did not meet Nikon’s internal quality standards. In extremely rare cases, this may cause the battery to overheat and the exterior casing to become deformed. Batteries exhibiting this problem have only been confirmed in the Nikon manufacturing process. We have received no reports of this problem from the market. Therefore, in order to ensure the safety of our customers and their equipment, we have initiated a voluntary replacement scheme for applicable products.
Customers using an applicable EN-EL15 battery may request a replacement battery. If the 9th digit of the EN-EL15 battery lot number is E or F then the battery needs to be replaced as it may be affected by this issue. More information can be found on Nikon's website