I should probably elaborate on the reason for the question.
A camera dealer was making the argument of using the EN-EL18 batteries only, as they last much longer and you can charge two at once (sort of) on the same charger, and if you have a D4 anyway that means only one type of battery to carry.
I also understood you had to take the grip off to replace the in-camera battery.
if the in-camera battery has to be there (and charged?) it sounds kind of awkward, and also seems to still require if travelling to take a charger for the in-camera battery as well.
If you can just leave it out entirely, that's intriging (though it's still an expensive piece of plastic and wires )
I find it useful to have a battery in both camera and grip ... that way, if I am on a shoot, I have double the battery time. I usually have the camera set to use the grip battery first, then the camera battery (it automatically changes ove). Then if I run through the camera battery, I can easily pop another in the grip (I usually carry a spare with me), essentially giving me the use of 3 batteries in succession, with only 1 change.
Very handy when out in the field for a long day of shooting.
But if you use the EN-EL18 in the grip as proposed in the original post you already have nearly double the capacity of a EN-EL15 in the camera. Also if you also have a D4 that requires the EN-EL18 you have to take only one battery charger on the road.
Gary in SE Michigan, USA. Nikonians membership - My most important photographic investment, after the camera. D4, D810, D300 (720nm IR conversion), D90, F6, FM3a (black), FM2n (chrome) YashicaMat 124, Graflex Speed Graphic 4x5 My Nikonians Gallery & Our Chapter Gallery
with a battery in the grip you do t need to have a battery in the camera to operate the camera ..
I have not totally tested this out but with a battery in both the camera as well as in the grip the camera appears to use the grip battery first leaving a full charge in the camera battery .. ie the camera battery would be the back up battery ..
>I have not totally tested this out but with a battery in both >the camera as well as in the grip the camera appears to use >the grip battery first leaving a full charge in the camera >battery .. ie the camera battery would be the back up battery
There's a menu option that determines that, what I wasn't sure about is whether it can be really completely dead or missing. If you had a grip and had some of the grip batteries, one might decide just never to even put a battery in the camera -- save a few ounces, but also save ever having to remove the grip, and only travel with one type of charger.