Need to know is their is a battery in the EGX300 and its function
Battery in EGX300
Yes that the EGX300 has a V3.0 lithium cell used and to provide power to the real time clock (RTC) when control power is removed.
During manufacture of the EGX the RTC is configured not to use battery power. This prevents any current drain from the battery during storage.
Once the EGX is powered up and the user sets the Date/Time the RTC is reconfigured to use the battery when EGX power is removed.
After the RTC is configured with the user date/time, the battery (and date/time settings) will last for 10 years with the EGX powered off. When the EGX is powered on the battery is not used.