What could cause a memory problem with Nikon D7100?

Question

I have a problem with my Nikon D7100: it does not keep the chosen settings over time. For example, if I set the settings to take a picture at ISO 500 and after a series of shots it goes to ISO 1000. Or I set it to take the shot only in jpg and it reconfigures to take the shot in RAW.

The same thing happens to me with the menu settings; for example, if I set the internal brightness of the camera to +3, turn the camera off, turn it back on and it is +4 as it came from the factory.

What could be causing this - is it possible that it is a problem of some internal battery?

Answer 1

Do you leave the main battery in, with a decent amount of charge left, when the camera is not in use?

I don't think these cameras have the equivalent of a CMOS battery which may fade over time, but I think they do use a capacitor to hold a small charge covering such as battery removal, or leaving perhaps a day or three without a battery, without losing internal settings.

There's a chance after 10 years any capacitor may itself be losing capacity, but keeping a reasonably-charged main battery in it ought to overcome that.
I've never left mine more than a few minutes without the main removable battery in it, so I don't know how long it would be expected to retain settings without one.