Emerson CKD9918 Owner's Manual page 7

Battery Back Up System
This unit uses a single CR2032 battery (not included) to maintain the Time,
Alarm time and Radio preset stations settings in the event that it is accidentally
unplugged, or you experience a temporary power failure. We recommend that
you install a well-known brand of Lithium battery for longest life and best
performance.
Installing and replacing the backup battery
1.) Use screw driver to remove the screw that secures the battery compartment
at the bottom of the unit,and move out the battery cartridge from the battery
compartment
2.) Insert a new battery in the battery cartridge with " + " side facing up.
3.) Insert the battery cartridge back into the unit and secure it with the screw.
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If the power is interrupted the clock display will go off but the battery will
maintain the Time, Alarm time and Radio preset stations settings. When power
is restored the time display will be correct and the alarm time and preset radio
stations will also be maintained.
If you notice that the time is wrong you probably experienced a power failure.
This could have been caused by a weak battery. Reset the clock and replace
the battery as soon as possible.
NOTE: The battery back up system will not work unless you have installed the
battery (CR2032, not included). Please see above for installation.
After you replaced the new battery, it will be necessary to re-enter the stations
in radio preset memories and reset the clock setting.
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