Navilite NNYXSB Emergency Light Replacement Battery 3.6V 1800mAh

Navilite NNYXSB — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 1800mAh Ni-MH replacement cell for the Navilite NNYXSB emergency lighting unit. It restores backup power to emergency exit lights and evacuation fixtures that have lost capacity or failed a duration test. Dimensions are 52.45 x 43.50 x 14.68mm — confirm these against your existing cell before ordering.

• NNYXSB fitting compatibility: This cell matches the voltage rail and physical footprint of the original NNYXSB unit. The charge controller in this fitting expects a 3.6V Ni-MH cell with a specific float acceptance window — swapping to a different chemistry or voltage will trigger a fault condition.
• Bench tested on actual hardware: We cycled this cell through a full discharge and timed recharge sequence. The BMS accepted the cell without fault, and the charge indicator transitioned from red to green within the expected window at full float voltage.
• First test cycle after installation: Within 24 hours of fitting, press and hold the test button for the full rated duration. This confirms the cell accepts load under real conditions and lets the charge controller register the new cell capacity before your next scheduled compliance inspection.

Charge indicator staying red after new battery installation

A cell sitting in storage arrives at a reduced state of charge — often below the float acceptance window the NNYXSB charge controller checks on startup. When the controller reads a voltage below its threshold, it holds the fault or charging indicator red rather than progressing to green. This is not a faulty cell. Leave the fitting powered on mains for 24 hours and the controller will complete its charge cycle and update the indicator. If the LED has not switched to green after 48 hours, measure the cell voltage directly — it should read at or above 4.3V when fully charged.

Emergency light dims noticeably partway through a duration test

A new Ni-MH cell does not always deliver full rated capacity on its first activation — this is normal for this chemistry and is not a defective cell. The cell needs at least one complete charge and discharge cycle before it reaches 1800mAh. If the light dims early during testing, recharge fully on mains for 24 hours and run the test again. A cell that still dims after two full cycles should be checked for a damaged tab connection inside the fitting.