Calculate a fire alarm battery duty estimate
Add standby current multiplied by standby hours to full alarm current multiplied by alarm hours. Multiply those amp-hours by the capacity factor required for the project.
Backup battery worksheet
Enter the standby and full alarm load from the actual panel, modules and notification appliances. Use the required duty times and factor from the approved design.
Worksheet only. Fire alarm capacity, charger compatibility, inspection and code requirements need approval by the applicable authority and qualified designer.
Planning example & assumptions
Enter currents from manufacturer documentation for the entire connected system. The editable example is a worksheet, not a statement of the duty cycle your job requires. Confirm applicable code edition, authority requirements, battery discharge characteristics and the panel charger’s permitted capacity with the approved designer.
Common planning questions
What formula does the battery worksheet use?
Required Ah = (standby amps × standby hours + alarm amps × alarm minutes ÷ 60) × capacity factor. Enter the duty cycle and factor required for your approved design.
Do batteries in series double amp-hour capacity?
Identical batteries in series increase voltage while retaining the amp-hour rating of one battery. Use the rating of the complete approved battery configuration and confirm charger compatibility. This worksheet does not approve a fire alarm design.