1. What is the BSIA Battery Size Formula?

The BSIA (British Security Industry Association) battery size formula calculates the required battery capacity (in ampere-hours) for security systems based on standby current, alarm current, and their respective durations.

2. How Does the Calculator Work?

The calculator uses the BSIA formula:

Where:

• \( Standby \) — Current drawn during standby mode (amps)
• \( Hours \) — Duration of standby operation (hours)
• \( Alarm \) — Current drawn during alarm mode (amps)
• \( Minutes \) — Duration of alarm operation (minutes)

Explanation: The formula calculates total charge required by summing the standby and alarm current demands, converting minutes to hours for the alarm component.

3. Importance of Battery Sizing

Details: Proper battery sizing ensures security systems remain operational during power outages for the required duration, meeting regulatory requirements and maintaining system reliability.

4. Using the Calculator

Tips: Enter standby current in amps, standby duration in hours, alarm current in amps, and alarm duration in minutes. All values must be non-negative.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical standby current for security systems?
A: Standby currents typically range from 0.1A to 2A depending on system size and features.

Q2: How long should batteries last in standby?
A: BSIA recommends minimum 24 hours standby with 30 minutes alarm, but specific requirements vary by application.

Q3: Should I add a safety margin to the calculated size?
A: Yes, it's recommended to add 20-30% to account for battery aging and temperature effects.

Q4: What battery types are used in security systems?
A: Sealed lead-acid (SLA) batteries are most common due to their reliability and maintenance-free operation.

Q5: How often should batteries be replaced?
A: Typically every 3-5 years, or when capacity drops below 80% of rated capacity.