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Advanced Fire Alarm Battery Equation:
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The Advanced Fire Alarm Battery calculation determines the required battery capacity (in ampere-hours) for a fire alarm system, accounting for both advanced sensor current draw and notification appliance current over a specified time period, with a 25% safety factor.
The calculator uses the equation:
Where:
Explanation: The equation calculates the total energy requirement for both system components during the backup period, then adds a 25% safety margin to ensure reliable operation.
Details: Proper battery sizing is critical for fire alarm system reliability during power outages. Undersized batteries may fail to maintain system operation for the required duration, while oversized batteries increase cost and space requirements unnecessarily.
Tips: Enter the current draw for advanced sensors and notification appliances in amps, and the required backup time in hours. All values must be positive numbers.
Q1: Why is there a 25% safety factor?
A: The safety factor accounts for battery aging, temperature effects, and other variables that may reduce actual battery capacity below rated capacity.
Q2: How do I determine the current draw values?
A: Current draw values should be obtained from manufacturer specifications for all connected devices in the system.
Q3: What backup time should I use?
A: Backup time requirements are typically specified by local fire codes, often 24 hours of standby plus 5 minutes of alarm.
Q4: Does this account for battery efficiency?
A: The 25% safety factor helps account for efficiency losses, but for precise calculations, consult battery manufacturer data.
Q5: Should I round up the calculated Ah value?
A: Yes, always select a battery with equal or greater capacity than the calculated value, considering standard battery sizes.