# Batteries - Siemens Cerberus PRO FC721 Technical Manual

Fire control panel.

Installation
6
Power supply - mains voltage connection

## 6.4.2 Batteries

50 | 118
Building Technologies
Fire Safety
Calculating the battery capacity
Determine the battery capacity with the following formula:
K
= (I
* t
+ I
Batt
R total
R
A total
K
Battery capacity in [Ah]
Batt
I
Sum of operating current of all consumers in quiescent condition [A]
R total
I
Sum of operating current of all consumers in alarm condition [A]
A total
t
Desired emergency power supply duration in quiescent condition [h]
R
t
Desired emergency power supply duration in alarm condition [h]
A
(standard 0.5 h)
k
Correction factor for discharge
dis
k
= 1.1 with ≤12-hour emergency power supply duration. In the
dis
event of a longer emergency power supply duration, the factor can
be omitted.
k
Correction factor for aging
age
k
= 1.25 if the desired emergency power supply duration is ≤24
age
h (according to DIN VDE 0833, part 2). In all other cases, the
factor can be omitted.
Example
K
= ((I
* t
) * k
Batt
R total
R
For 12 h emergency power supply duration:
= ((0.9 A * 12 h) * 1.1 * 1.25) + ((3.5 A * 0.5 h) * 1.1 * 1.25) = 17.2 Ah
For 24 h emergency power supply duration:
= ((0,9 A * 24 h) * 1.25) + ((3.5 A * 0.5 h) * 1.25) = 29.2 Ah
For 72 h emergency power supply duration:
= (0.9 A * 72 h) + (3.5 A * 0.5 h) = 66.5 Ah
* t
) * k
* k
A
dis
age
* k
) + ((I
* t
) * k
dis
age
A total
A
* k
)
dis
age
A6V10211100_f_en_--
2015-12-15