The camera has an internal rechargeable battery for maintaining the date, time, and other settings. This information remains saved in the camera regardless of whether the main battery pack is installed or not, or whether the power if off or on. The internal battery is continually recharged when the camera is turned on and in use.
NOTE: The internal battery discharges gradually if the camera is only used for short periods of time. If the camera is not used at all for approximately 3 months, the internal battery becomes completely discharged.