Document No: LT0255 F3200/NDU AS4428.1 Installation Manual
Configuring a FIP
Issue 1.04 30 June 2004 Page 4-5
EXAMPLE BATTERY/CHARGER CALCULATIONS (CONTINUED)
An external 24V bell drawing 30mA.
A PA0765 T-Gen50 (Tones and Fault Monitoring) with a 16W speaker load.
Calculate the required battery capacity and check the power supply capacity.
Steps
1. The quiescent load (Iq) for the mains fail situation is:
130mA (FIP including one 8ZM)
+ 82mA (second 8ZM, all AZCs enabled)
+ 4mA (third 8ZM, basic current only)
+ 4 x 10mA (third 8ZM, current for 4 AZCs)
+ 42mA (detector current)
+ 6mA (8RM, supervision enabled)
+ 42mA
(PA0765 T-Gen with Fault relay enabled)
346mA
Say Iq = 0.35A for mains off.
The quiescent load for mains on is Iq plus the door holders (In = 0.35A) i.e. 0.70A. (It
was purely coincidence that Iq = In).
2. Say, for example, that the 2 zones in alarm can, at most, turn on 3 of the 5 module
relays plus the External Bell, the T-Gen Warning System and the Anc 1 load.
The alarm load for 2 zones in alarm is therefore:
275mA (FIP including 1 8ZM, 2 zone alarm, MAF relays)
+ 82mA (second 8ZM, quiescent only)
+ 44mA (third 8ZM, quiescent only)
+ 42mA (detector current)
+ 6mA (basic 8RM current)
+ 3 x 11mA (3 relays on 8RM)
+ 3 x 50mA (loads on 3 relays)
+ 100mA (Ancillary 1 relay load)
+ 30mA (Bell load)
+ 704mA
(T-Gen50 alarm load of 16/50 x 2.2A).
1466mA
Say Ia = 1.47A (the door holders are switched off in alarm).
3. Cap (5 hr) = 5 x 0.35 + 0.66 x 1.47 Ahr = 2.72 Ahr
4. Battery charger current required is:
Ia (1.47A) is greater than Iq + In, (0.70A), therefore:
Ic = 1.47A + (2.72/24) x 1.25 = 1.61A (where the 1.25 allows for charging efficiency e
of 0.8) i.e. 3A is sufficient.
5. Battery capacity
Cap (24 hr) = [(24 x 0.35) + 0.66 x 1.47] x 1.25 = 11.7Ah. (where the 1.25 allows for
battery deterioration over lifetime to 80% of new value).
Two 12V, 12 Ahr sealed batteries from the list in Section 3.3.3. are the smallest
batteries that are suitable.
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