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Appendix A: Secondary Power Calculations Calculating the Battery Capacity
38
PDRP-1001 Instruction Manual PN 50734:D0 04/06/01
Calculating the Battery Capacity
Use this table to determine the battery capacity required by the system.
Table 2 Amp Hour Calculations
The battery charger in this panel will charge a maximum of 18 AH of batteries within 48 hours (7 AH
minimum). Batteries larger than 12 AH will require a UL-listed battery cabinet (e.g. BB-17).
Select a battery with an equal or greater AH rating than the value obtained in the table above.
Note: Batteries must be lead-acid type.
Standby Battery Current
(from Table 1)
[ ] amps X
Required Standby Time in Hours
(typically 24
1
, 60
2
or 90
3
hours)
[ ] hrs
1. NFPA 72 Central Station and Local and Proprietary Fire Alarm Systems require 24 hours of standby time.
2. NFPA 72 Auxiliary and Remote Station Fire Alarm Systems require 60 hours of standby time.
3. Factory Mutual Systems require 90 hours of standby for preaction and deluge sprinkler systems.
=
Standby
Amp Hours
Enter:
0.25 for 5 minutes in alarm, or
0.50 for 10 minutes in alarm
Alarm
4
Amp Hours
4. Alarm AH assumes a maximum system draw of 3 amps in alarm for 5 minutes (0.25 AH) or for 10 minutes (0.5AH).
Total Standby and Alarm Load +
Multiply by derating factor X 1.2
Battery size required in AH =