Smart Connect
Single Loop Touch Screen Panel
Doc: GLT-229-7-1
86
Issue: 3
Date: 12/05/2017
13.4 STANDBY BATTERY CALCULATION
In order to calculate the standby battery size required, the following formula can be used:-
Battery Size (Standby time in Amp Hours) = 1.25 x [(T
ALM
x I
ALM
) + (T
SBY
x (I
QP
+ I
QZ
))]
Where:
T
ALM
= Maximum time in hours required for the alarm [½ hour is most common time]
I
ALM
= Total Alarm Current in amps
I
ALM
-SND = Alarm Current of Sounders in amps
T
SBY
= Standby time in hours for the system after mains failure [normally 24, 48 or 72 hr]
I
QP
= Quiescent current in amps of control panel in fault condition [because of mains failure]
IAP
= Alarm current in amps of control panel
IQL
= Quiescent current in amps of all loop devices.
Typical Example:
A system comprises of a 1 Loop Smart Connect panel, with 80 Addressable Optical Smoke Detectors, 15 Addressable Manual Call
Points, 20 Sounders and the required standby is 24 hours. It will need to operate in alarm for ½ hour.
Calculate the battery size required.
T
ALM
= 0.5 Hr
I
ALM-SND
= 20 x 0.004 =0.08A
T
SBY
= 24 Hr
I
QP
= 0.20A
I
AP
= 0.19A
I
QL
= 80 x 0.00044 + 15 x 0.001 + 20 x 0.0005 = 0.0602A
I
ALM
= I
ALM-SND
+ I
AP
+ I
QL
= 0.08 + 0.19 + 0.0602 = 0.3302
Therefore using the equation:
Battery Size (Standby time in Amp Hours) = 1.25 x [( T
ALM
x I
ALM
) + ( T
SBY
x ( I
QP
+ I
QL
))]
Battery Size (Standby time in Amp Hours) = 1.25 x [(0.5 x 0.33) + (24 x (0.20 + 0.06))]
Battery Size (Standby time in Amp Hours) = 1.25 x [(0.5 x 0.33) + (24 x 0.26)]
Battery Size (Standby time in Amp Hours) = 1.25 x [0.165 + 6.24]
Battery Size (Standby time in Amp Hours) = 1.25 x 6.405
Battery Size (Standby time in Amp Hours) = 8.01 Amp Hours
For a system like this, 2 x 12V sealed lead acid batteries must be used each with a capacity greater than 8.01 Ah. For example,
12Ah
