It's a bit smaller, and I imagine space is at a premium in that smaller body. It also seems to have connections that are not so exposed, much lessening the chance of an accidental short across the terminals.
I'm pretty sure it's the terminal changes that drove this. The FAA has actually considered banning batteries without sufficient protection from airliners. The rules that were proposed but not adopted would have rendered most cell phones, virtually all cameras and most laptops non-flying. The rules fell into the category of "what could they possibly be thinking" but they scared a lot of industries into redesigning stuff.
You know, the problems that you read about every day? Yeah, I missed them too. I checked with some of our battery people, who think it's hogwash. This is one time that I think the lobbyists were on the right side of things.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!
I don't think the exposed-terminal issue is especially new. The EN-EL4, which came out in what, 2003? has recessed terminals. The EN-EL3 design is truly an old one. Perhaps what we should be surprised about is that Nikon extended it as long as they did.
Since the video features, used typically for a longer period, draw more current, they probably wanted to get a redesigned battery that would give suitable video recording time above what a D90 battery could provide. They also rearranged the interior of the camera a little, possibly to get the new larger VF and different mirror box in place, in essentially the exact same size camera body. The only dimension change is 2mm increased height. D90 132x103x77mm D7k 132x105x77mm
I think that I read that you can now shoot 20 min of consecutive video. I am not sure if this weighed into the new battery design or not, but perhaps?
I really wish that they would have found a way to use the old batteries. The last thing that I need are 3 different batteries and charges now. The battery change is the biggest drawback to me purchasing a D7000. Other than this issue, it "sounds like a winner and a camera that I would want to purchase.