Fire Alarm Battery Calculator
Calculate fire alarm and Fire-Lite style panel battery backup from standby current, alarm load, derating, and spare capacity.
Open ToolIntruder Alarm Battery Calculator
Free intruder alarm battery calculator for burglar alarm panels, siren load, auxiliary load, standby hours, alarm duration, derating, and spare capacity.
What is an intruder alarm battery calculator?
An intruder alarm battery calculator estimates the backup battery capacity needed for a burglar alarm or security alarm panel. It adds standby current and auxiliary device current for the required standby duration, then adds alarm current and auxiliary current for the alarm or siren duration. The result is adjusted for usable battery derating and spare capacity before recommending a standard battery size. It is useful for intruder alarm panels, PIR devices, keypads, magnetic contacts, external sirens, diallers, communicators, and small security systems. Final selection must still follow the alarm panel manufacturer data, charger output limit, local security standard, battery temperature, battery age allowance, insurance requirement, and client specification. Load the sample first, then replace the currents with values from the actual panel and device datasheets.
Inputs
Forms are empty on load. Use sample data to preview the workflow or enter your own project values.
Learn more
Formula logic, use cases, assumptions, and limits for this tool.
How this tool helps
Use this for intruder alarm, burglar alarm, and security panel backup battery planning before selecting the final battery size from the panel manufacturer data.
Assumptions and limits
This tool provides a planning-level result. It does not replace detailed engineering design, approved software, manufacturer data, authority requirements, or project specifications.
Typical use cases
- Early estimation and tender support.
- BOQ sanity checking and technical review.
- Site discussion before final engineering verification.
- Comparison of alternatives using consistent assumptions.
Result interpretation
Read the recommendation, warning, and confidence sections together. A result without warnings is still not an approval; it only means the entered values did not trigger built-in planning alerts.
Quick answer for common searches
Intruder alarm battery sizing depends on standby current, alarm current, backup duration, usable derating, and spare capacity. Use real device current where available.
Useful search phrases covered by this page
- intruder alarm battery calculator
- alarm battery backup calculator
- security alarm battery sizing
Next checks
Input definitions and typical values
These notes explain what each input means and which values usually produce a more reliable planning result.
Standby current mA
Electrical current or battery input. Use measured standby/alarm current or manufacturer datasheet values for better results.
Alarm current mA
Electrical current or battery input. Use measured standby/alarm current or manufacturer datasheet values for better results.
Auxiliary device current mA
Electrical current or battery input. Use measured standby/alarm current or manufacturer datasheet values for better results.
Standby duration hours
Project input used directly in the calculation. Use measured, scheduled, manufacturer, or authority-approved values where available.
Alarm/siren duration minutes
Project input used directly in the calculation. Use measured, scheduled, manufacturer, or authority-approved values where available.
Usable battery derating %
Electrical current or battery input. Use measured standby/alarm current or manufacturer datasheet values for better results.
Spare capacity %
Future spare capacity. 10-25% is common in early MEP planning, depending on client growth and infrastructure constraints.
Practical verification checklist
- Confirm the selected standard profile is suitable for the project location and authority.
- Replace sample values with project drawings, schedules, equipment data, or measured site values.
- Review warnings, methodology, and PDF report before using the result outside early planning.
- Verify final decisions against official standards, manufacturer data, consultant specifications, and local approvals.
Related tools
Other tools in ELV and fire alarm battery planning.
Calculation methodology
Battery Ah = standby current plus auxiliary current for standby hours, plus alarm current plus auxiliary current for alarm duration, adjusted for derating and spare capacity.
Inputs are treated as planning assumptions. The calculator shows warnings when entered values fall outside practical thresholds or selected standard-profile limits.
Version history
- v1.3.41: Added from Search Console query demand for intruder alarm battery calculator.
Stage 2 roadmap: optional saved projects, dashboards, and shared calculation history without forcing login for free use.
Trust and verification
Every result includes assumptions, warning logic, and a downloadable report. Final engineering decisions still need qualified review, local authority approval, manufacturer data, and project specifications.
Worked example
Use the sample data button to load a realistic scenario, then download the PDF report to review inputs, results, methodology, warnings, and disclaimers in one place.