Page 6 of 12 DocNo.DCP0001326 DSM 05/01/05 rev7
The P2.200LS is designed to operate with two 12 Volt VRLA batteries connected in series.
BS5839-8 1988 requires that batteries must be capable of operating the system according to the project
requirements (normally 24 Hours in a quiescent current state plus 30 minutes in full alarm). It also requires
that batteries be sized so as to provide 25% overcapacity to allow for loss of capacity over time.
It is also necessary to allow for the current drawn by any ancillary equipment connected to the Auxiliary power
output. Auxiliary devices should be connected to different P2.200LS amplifiers in order to spread the load as
evenly as is practical.
Quiescent Battery capacity
The current drawn in the quiescent state is 75 mA per amplifier module, 150 mA total.
The current drawn in the quiescent state with all fault indicators lit is 150 mA per module, 300 mA total.
Therefore, for worst case, the power drawn over 24 Hours is 7.2 AHr.
Alarm Condition Battery Capacity
It is difficult to predict the exact current drawn in alarm condition so the following approximation is used.
Emergency messages consist of a tone, silence, message and silence.
The average power content of speech is approximately 5%.
The average power content of a tone is approximately 20%
The average power content of silence is nil.
A conservative estimate of current draw is therefore 10% of the peak.
The peak current drawn from each amplifier channel is 11 Amps, 22 Amps total.
10% of the peak value is therefore 2.2 Amps or, for 30 minutes, 1.1 AHr.
However, batteries must be de-rated by 50% at high discharge rates and so a figure of 2.2 AHr is taken
If 60 minutes in alarm is required, 4.4 AHr will be required.
Total Battery Capacity
Add alarm state battery capacity to the quiescent capacity and the capacity required is 9.4 AHr
Add 1/3 to allow for a 25% loss of capacity over time and the smallest battery that can be used is 12.5 AHr.
The smallest standard battery above this size is 18 AHr and 27 AHr gives even more spare capacity.
Additional battery capacity for ancillary equipment
Add the capacity required for any ancillary equipment, plus one third for battery aging. These figures do not
change in an alarm condition.
Worst case quiescent current drawn at 24V d.c.
SS2N
= 75 mA
= 1.84 AHr + 1/3
= 2.44 AHr
Psiren
= 50 mA
= 1.23 AHr + 1/3
= 1.63 AHr
FCB
= 50 mA
= 1.23 AHr + 1/3
= 1.63AHr
Integrity Mainframe
= 300 mA
= 7.35 AHr + 1/3
= 9.78 AHr
MP2
= 50 mA
= 1.23 AHr + 1/3
= 1.60 AHr
MPP panel (any)
= 150 mA (all LEDs lit)
= 3.68 AHr + 1/3
= 4.89 AHr
Batteries must be connected via a suitable fuse. We recommend DIN mounted cartridge fuse holders ref
RS371-0340 and 20A RS230-3496 cartridge fuses.
Correct Power-up Sequence
Plug in mains connector
Make sure external battery fuse is out of circuit
Connect battery connector to amplifier
Switch on mains
Connect battery fuse
Power-related fault indicators should extinguish
If the batteries are connected before the mains supply is turned on the inrush current will weaken the internal
battery fuse.
DC power operation and Battery Calculation
