D3100 - Asking Date Time Settings Every time I switch

Hey,

My D3100 is asking to set up the date and time every time i am loading the battery to use the camera, Any Idea? Is there any internal battery like CMOS Battery in Computer that I need to change?

There is an internal battery that keeps the settings and time going while the main battery is out, but it is not user-changeable.

How often & for how long do you take the main battery out? I ask as the main battery is used to charge the smaller internal battery. Try giving your main battery a full charge, put it in the camera and leave it in for days and see if it charges the internal one - If it doesn't then it will be a repair job to have the internal battery replaced.

They say the internal battery should hold for a month or more if fully charged. Like Steve said, it can take a couple of days to fully recharge the internal battery from the main battery. Evaluate your usage with this in mind to decide if you have a problem. I seldom use my d3100 anymore, but I keep the main battery installed all the time.

If the time between "NO Main Battery" is more than a month, then you will rectify the problem by just keeping the main battery for a few days. Otherwise your internal battery is gone. Happens some times. Similar case was with my desktop PC. The problem stopped once the battery was replaced.