Installation manual
D9124 Operation & Installation Manual
Page 37
© 1996 Radionics
74-06799-000-D 2/96
Standby Battery Calculations For
Fire Alarm Applications
Standby Battery and Current Rating Chart first:
You must calculate totals for columns
B and C in the
Auxiliary Current and Standby Battery Requirements
section,
Calculations
for 12 VDC Devices
before you can complete the calculations below.
Calculations for D9112LTB and 12 VDC
Initiating and Indicating Devices
Central Station or Local Systems (24 Hour Standby)
Central Station or Local Systems require 24 hours of standby plus five minutes of alarm
operation at the end of the 24 hour period. A single battery is sometimes adequate for
Central Station Systems, but you must install two batteries to meet the basic standby
requirements for a Local System installation. You must use battery ampere hour (Ah)
calculations to verify compliance. The following formula includes the calculation for five
minutes of alarm operation at the end of the 24 hour period, as well as a 10% contingency
factor which allows for depletion of battery capacity with age.
Central Stations or Local Systems Ampere-Hour Calculation Formula
Use totals from
Calculations for 12 VDC Devices
Total B Hours Total C Hours Contingency Total Ah
( ________ x 24 ) + ( _______ x .083 ) + 10% = __________
Total Ah requirements must not exceed Ah capacity of batteries:
Two D126 Batteries = 14 Ah
Two D1218 Batteries = 34.4Ah
Remote Station or Auxiliary Systems (60 Hour Standby)
Remote Station or Auxiliary Systems require 60 hours of standby plus five minutes of alarm
operation at the end of the 60 hour period. A UL Listed power supply with additional batteries
installed in a separate D9109 or D9109G enclosure may be required in the D9124 system
to meet the basic standby requirements for a Remote Station or Auxiliary System installation.
You must use battery ampere hour (Ah) calculations to verify compliance. The following
formula includes the calculation for five minutes of alarm operation at the end of the 60 hour
period, as well as a 10% contingency factor which allows for depletion of battery capacity
with age.
Remote Station or Auxiliary Systems Ampere-Hour Calculation Formula
Use totals from
Calculations for 12 VDC Devices
Total B Hours Total C Hours Contingency Total Ah
( ________ x 60 ) + ( _______ x .083 ) + 10% = __________
Total Ah requirements must not exceed Ah capacity of batteries:
Two D126 Batteries = 14 Ah
Two D1218 Batteries = 34.4Ah