Originally posted by Heinrich Lohmann We have an original Q, Q10, Q7 and a Q S1, none of them lose their date when changing batteries. We make sure that there is always a charged battery in the camera (we have about 6 spares) My understanding is that there is NO secondary battery in the camera but a sort of capacitor that keeps things going while one change the battery. If you leave the battery out too long the capacitor loses it's charge and you will have to reset things.
That fits my experience. With each of my K-30 and Q-7, I was interrupted by something in the middle of switching batteries (in one case, I took the battery out of the Q-7 before fetching the replacement from my camera bag ... and then my wife called me to dinner). By the time I remembered what I had been doing, and came back to the camera, it had forgotten the time. I don't consider this to be a big deal, but if I don't want to have to reset the clock, I have to make switching batteries an uninterpretable task; in particular, I need to have the replacement next to me before I take the current batter out).