Battery Calculation Basis

The required battery capacity for each fire alarm panel is calculated using the following formula:

$$Minimum\>Capacity = \Big((P_{standby} + \sum A_{standby}) \times T_{standby} + (P_{alarm} + \sum A_{alarm}) \times T_{alarm} \Big) \times Safety\>Factor$$

$P_{standby}$ and $P_{alarm}$ are the Standby Load ▾ and Alarm Load ▾ for the panel itself and any internal components not shown on the Revit model, such as displays, interfaces, communication modules, or expanders. These values are set in the Family Edit and Panel Edit commands.

$A_{standby}$ and $A_{alarm}$ are the Standby Load ▾ and Alarm Load ▾ for each device circuited to the panel. These values are set in the Family Edit and Device Edit commands.

$T_{standby}$ and $T_{alarm}$ are the minimum durations for which the battery must be able to power devices in standby mode and alarm mode per NFPA 72 10.6.7.2. The default values are $24\>hours$ for standby mode and $15\>minutes$ for alarm mode. These values can be modified in the Project Options command.

A $Safety\>Factor$ is applied to the final sum per NFPA 72 10.6.7.2.14. The default value is $1.25$ but can be modified in the Project Options command.