Does anyone use this grip empty and have a problem with the camera battery draining? If I leave my empty grip on the camera (purchased for the better grip not really for extra charge) for a few days, my battery will show noticeable draining. Does this go away if I put AA's or an extra battery in the grip? Or will that just drain fast too? Since I got my grip which is excellent in every other way, I have to charge my battery about twice as often.