Nikon F6 Internal Battery

Nikon MB-40 Battery Options. On left, the BL-3 Adaptor allows use of EN-EL4a batteries. On right, the MS-40 adaptor allows use of 8 AA batteries.
Nikon MB-40 Battery Options. On left, the BL-3 Adaptor allows use of EN-EL4a batteries. On right, the MS-40 adaptor allows use of 8 AA batteries.

UPDATE: 6/18/24
Well, it happened to me. Somehow after leaving the F6 stored without batteries for a period of time, the internal battery seems to have died. No amount of new CR123 batteries have been able to resuscitate the internal battery. Now, like everyone else, I need to reset the clock when I load new batteries. 

The good news is, much of the other information seems intact. The roll count, for example. So the paragraph originally on this page, about being able to simply load new batteries and the internal should recharge – has been removed.

Other Power Sources:
CR123 batteries
AA Batteries via the MB-40 Grip
Nikon EN-EL4a Li-Ion 11.1V rechargeable battery