1. What is the BSIA Alarm Battery Calculation?

The BSIA (British Security Industry Association) alarm battery calculation determines the required battery capacity (in Amp-hours) for security alarm systems, accounting for both quiescent and alarm current draw over a 24-hour period with a safety margin.

2. How Does the Calculator Work?

The calculator uses the BSIA equation:

Where:

• \( BSIA_{Quiescent} \) — Standby current consumption in milliamps (mA)
• \( Alarm \) — Current draw during alarm in milliamps (mA)
• \( 24 h \) — 24 hour standby period
• \( 0.5 h \) — 30 minutes alarm duration
• \( Margin \) — Safety factor (typically 1.2-1.5)

Explanation: The equation calculates total energy consumption during standby and alarm states, converts to Amp-hours, and applies a safety margin.

3. Importance of Proper Battery Sizing

Details: Correct battery sizing ensures alarm systems remain operational during power outages and can trigger alarms when needed. Undersized batteries may fail when needed most.

4. Using the Calculator

Tips:

• Measure quiescent current from manufacturer specs or actual measurements
• Include all alarm current draws (sounder, strobe, communicator)
• Typical margin is 1.2 (20% extra capacity) for standard applications

5. Frequently Asked Questions (FAQ)

Q1: Why include a margin in the calculation?
A: The margin accounts for battery aging, temperature effects, and manufacturing variations to ensure reliable operation throughout battery life.

Q2: What's a typical quiescent current for alarm panels?
A: Modern panels typically draw 50-200mA in standby, but always check manufacturer specifications.

Q3: Why only 0.5 hours for alarm duration?
A: BSIA standards assume a maximum 30 minute alarm period before mains power would typically be restored or system reset.

Q4: How often should batteries be replaced?
A: Typically every 3-5 years, or when capacity drops below 80% of rated value.

Q5: Does temperature affect battery capacity?
A: Yes, capacity decreases in cold temperatures. In cold environments, use larger margins or temperature-compensated calculations.