1. What is Fire Alarm Battery Standby Time?

The Fire Alarm Battery Standby Time is the duration a fire alarm system's backup battery can power the system in standby mode. It's crucial for ensuring the system remains operational during power outages.

2. How Does the Calculator Work?

The calculator uses the following equation:

Where:

• \( \text{Battery Ah} \) — Battery capacity in amp-hours
• \( \text{Standby A} \) — Current drawn by system in standby mode (amps)

Explanation: The equation calculates how long the battery can supply the required standby current before being depleted.

3. Importance of Standby Time Calculation

Details: Fire codes typically require minimum standby times (often 24-72 hours) to ensure system operation during extended power outages. Accurate calculation ensures compliance and safety.

4. Using the Calculator

Tips: Enter battery capacity in amp-hours (Ah) and standby current in amps (A). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical standby current for fire alarm systems?
A: Standby current varies by system size but typically ranges from 0.1A to 2A for most commercial systems.

Q2: How much standby time is required by code?
A: NFPA 72 typically requires 24 hours of standby plus 5 minutes of alarm, but local codes may vary.

Q3: Should I derate the battery capacity?
A: Yes, for lead-acid batteries, use only 80% of rated capacity to account for aging and temperature effects.

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 standby time?
A: Yes, battery capacity decreases in cold temperatures - derate capacity by 1% per °F below 80°F (27°C).