I doubt that the metering system would chew much power over that time period. I'd assume most power is used by things that move - shutter/mirror, AF and VR, and you are unlikely to be using AF or VR.

Using the internal interval timer I shot 600 frames over a 48-hour period on my D300 and from memory had to change the battery once. However this was only mucking about so I doubt that the first battery was fully charged when I started.


Cheers.