Abus CITADEL Alarm Set Micral Fitting And Operating Instructions page 24

If the battery voltage is lower than 2,4 V, in the process of pushing the
button, the LED (11) will flash continuosly to prompt for replacement of
the battery.
Replace a discharged battery immediately. Only use batteries of
type CR2032. When inserting the battery, please pay attention to the
correct polarity!
To change battery, open the housing carefully with a screwdriver at
the arrow-marked points, as shown below:
Tecnical data
Power supply
Standby current
Transmitter current
Radio frequency
Transmitted power
Working temperature
24
SOS
DC 3 V CR2032
< 1 µA
< 20 mA
868 MHz
< 13 dBm
-10°C - +55°C
GB