Questions on Sigma backup NiMH batteries.

[Product_Support]

Issue

This article addresses common questions regarding the NiMH battery packs used in Sigma X96 controllers, including:

1. What is the average shelf life of these batteries?
2. Can the battery voltage be checked without disconnecting them from the controller?
3. Is there a recommended preventative maintenance interval for checking the batteries?

Product Line

Satchwell BAS & Sigma

Environment

Sigma UNC controllers

Cause

These questions typically arise during routine maintenance or troubleshooting of Sigma controllers, especially when assessing battery health or planning replacements.

Resolution

• Battery Shelf Life

  • NiMH cells degrade over time, especially in long-term storage.
  • Typical shelf life: Up to 2 years.
  • Risk: Prolonged storage can lead to internal short circuits, a known characteristic of NiMH chemistry.

• Measuring Battery Voltage

  • Direct measurement without disconnection is not recommended.
  • If the battery remains connected, the voltage reading will reflect the charge circuit, not the battery itself.
  • Recommended method:
    • Power down the controller completely (turn off both mains and battery switches).
    • Insert multimeter probes into the back of the battery connector to measure voltage.
  • Note: Voltage alone is not a reliable indicator of battery health.
    • For accurate assessment, measure the run-time on battery power or use a commercial battery analyzer.

• Preventative Maintenance Interval

  • No fixed interval is officially specified.
  • Why? Battery lifespan is influenced by several factors, especially ambient temperature.
  • Best practice: Monitor battery performance periodically and replace if degradation is observed.