Emergency power supply
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Building Technologies 008725_h_en_--
Fire Safety & Security Products 06.2011
36 Emergency power supply
36.1 Determining the battery capacity
Emergency current batteries available
FA2006-A1 A5Q00019356 12 V/24 Ah battery
1)
FA2007-A1 A5Q00022897 12 V/38 Ah battery
1)
FA2005-A1 A5Q00019677 12 V/15 Ah battery
1)
1) The battery capacities supplied may be slightly higher.
The values 15 Ah, 24 Ah and 38 Ah should be taken into account when defining
the battery capacities needed.
Nominal battery capacity
The nominal battery capacity is based on discharge over a period of 20 hours
Faster discharge results in drops in capacity:
With 12-hour discharge=: 9% drops (K = 1.1)
Battery aging
As the battery ages, capacity is reduced
A safety factor should be used for aging (total quiescent current × 1.25 or bat-
tery capacity × 0.8) > 24 h, according to DIN VDE 0833, Part 2 a safety factor
is no longer needed
Calculation
The battery capacity should be calculated individually!
Formula: Ah = A x h (with 72 h battery)
Ah = A x h x 1.25 (with 24 h battery)
Ah = A x h x 1.25 x 1.1 (with 12 h battery)
A = sum of quiescent current of all components (see chap. 36.2
)
h = operating period needed in hours
1.25 = safety factor for aging with 12 h and 24 h batteries only
1.1 (K) = drops in capacity with 12 h battery only
Ah = battery capacity in Ah
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