What is the New Silent Accelerated Test?

The New Silent Accelerated Test is a battery testing method described in Annex C of CAN/ULC-S536-19 and CAN/ULC-S537-19.

The test requires the battery to maintain at least 85% of its rated voltage after 5 minutes under a 5 ohm load.

This method verifies fire alarm system battery performance by applying a fixed resistive load directly across the batteries and observing how the voltage responds over a defined period.

According to Annex C, the test is performed by:

  • Disconnecting the batteries from the system
  • Applying a 5 ohm load resistor (minimum 200 watts) across the batteries
  • Maintaining the load for 5 minutes
  • Measuring and recording the battery voltage at the end of the test
  • Confirming that the battery voltage is not less than 85% of its rated voltage
  • Reconnecting the system and observing charging current

This process evaluates the battery's ability to maintain adequate voltage under sustained load conditions, helping identify weak or failing batteries.

What this Means in Practice

The Silent Accelerated Test:

  • Applies a real, continuous load (not a pulse or estimation)
  • Generates significant heat due to the resistive load
  • Requires careful control to ensure safe and consistent testing
  • Confirms the battery can maintain at least 85% of its rated voltage under load
  • Provides a reliable indication of battery performance under actual operating conditions

This method replaces traditional pulse load testers and battery capacitance testers, which are no longer permitted under these standards.

What Is The NSAT?

The NSAT (New Silent Accelerated Tester) is a purpose-built tool developed by Volt Verify Inc. to perform the New Silent Accelerated Test in the field.

It is specifically designed to:

  • Apply the required 5 ohm equivalent controlled load for 5 minutes
  • Measure how battery voltage holds during the test
  • Help technicians safely perform testing by controlling the considerable heat generated
  • Deliver consistent and repeatable results

The NSAT is CSA evaluated, providing additional confidence in its design and performance.


Summary

  • New Silent Accelerated Test = a resistive load test defined in Annex C (5 ohm, 5 minutes, ≥85% voltage requirement)
  • NSAT (New Silent Accelerated Tester) = the tool designed to perform this test safely and consistently

Together, they provide a modern, compliant, and practical approach to fire alarm battery testing.