> >I doubt that the D400 will use the EN-EL18 D4 battery. Most >likely the D400 will be a D800 size body and would use the >EN-EL15 from the D800, D600, and D7x00. Because it is much >larger, the EN-EL18 battery takes up too much space for a body >without a built in vertical grip.
You are right about the size. It is too big for a non-vertical grip body.