Emergency Power Supply; Determining The Battery Capacity - Siemens AlgoRex CS1140 Planning

36

Emergency power supply

36.1

Determining the battery capacity

Building Technologies
Fire Safety & Security Products
Emergency current batteries available
FA2006-A1

FA2007-A1

FA2005-A1

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=:

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
Ah = A x h x 1.25
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
A5Q00019356 12 V/24 Ah battery
A5Q00022897 12 V/38 Ah battery
A5Q00019677 12 V/15 Ah battery
9% drops (K = 1.1)
(with 72 h battery)
(with 24 h battery)
Emergency power supply
1)
1)
1)
)
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06.2011