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MS-9600LS Series Manual — P/N 52646:B2 2/12/2010 177
Calculating the Battery Size Power Supply Calculations
5.4 Calculating the Battery Size
Use Table 5.4 to calculate the total Standby and Alarm load in ampere hours (AH). This total load
determines the battery size (in AH), required to support the control panel under the loss of AC
power. Complete Table 5.4 as follows:
1. Enter the totals from Table 5.3 on page 176, Calculation Columns 2 and 3 where shown.
2. Enter the NFPA Standby and Alarm times (refer to ‘NFPA Requirements’ below).
3. Calculate the ampere hours for Standby and Alarm, then sum the Standby and Alarm ampere
hours.
4. Multiply the sum by the derating factor of 1.2 to calculate the proper battery size (in AH).
5. Write the ampere hour requirements on the Protected Premises label located inside the cabinet
door.
5.4.1 NFPA Battery Requirements
• NFPA 72 Local, Proprietary, Central, Auxiliary and Remote Station Fire Alarm Systems
require 24 hours of standby power followed by 5 minutes in alarm
• NFPA requires 24 hours of standby plus 15 minutes activation for audio systems. The total
ampere hours required cannot exceed 26 AH with an internal charger
5.4.2 Selecting and Locating Batteries
Select sealed lead acid batteries that meet or exceed the total ampere hours calculated in Table 5.4.
The control panel can charge batteries in the 12 AH to 26 AH range. The control panel cabinet is
capable of housing batteries up to 18 AH. Batteries larger than 18 AH require the BB-26, BB-55F,
or other UL-listed external battery cabinet.
Secondary Standby Load
(total from Table 5.3 Calculation
Column 3)
[ ]
Required Standby Time
(24 hours)
X[ ] = AH
Primary Alarm Load
(total from Table 5.3 Calculation
Column 2)
[ ]
Required Alarm Time
(for 5 min., enter 0.084,
for 10 min., enter 0.168)
X[ ] = AH
Sum of Standby and Alarm Ampere Hours = AH
Multiply by the Derating Factor X 1.2
Battery Size, Total Ampere Hours Required = AH
Table 5.4 Total Secondary Power Requirements at 24 VDC