Battery Calculator

Fire Alarm Panel — AS7240.2

Calculate the required battery capacity for your fire alarm panel based on quiescent and alarm loads. Generate a branded report for your records.

Battery Calculation

Quiescent Load

Alarm Load

Standby Time

Hours

Alarm Time

Hours

Installed Battery Capacity

Report Details

Site Name

Test Reference

Tested By

Required Capacity

—

Amp-hours (Ah)

Formula: 1.25 × ((Standby hrs × Quiescent) + (2 × (Alarm load × Alarm hrs)))

AS7240.2 — Battery Capacity Requirements

In the event of primary power failure, batteries must maintain the system in quiescent mode for the required standby period, then power two worst-case alarm zones for the required alarm duration. New batteries must provide at least 125% (L=1.25) of calculated capacity to account for 20% capacity loss over the battery's useful life. A capacity de-rating factor (F_C) of 2 is applied to the alarm load to account for discharge rate characteristics.

Where: C₂₀ = capacity at 20h discharge rate (Ah), I_Q = quiescent current, T_Q = standby time, F_C = de-rating factor (2), I_A = alarm current, T_A = alarm time, L = deterioration factor (1.25 new / 1.1 used)

Generated using the Essential Fire Services Battery Calculator

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All calculations should be verified by a qualified fire protection technician.