About this replacement
Neptolux N89 — 7.4V Li-ion Replacement Battery (175-8002)
This 7.4V, 2200mAh Li-ion battery replaces the original cell in the Neptolux N89 emergency lighting unit. It fits the N89 fitting directly, matching the OEM voltage rail and connector. Also cross-references part number 175-1196C.
- N89 fitting compatibility: The N89 charge controller expects a 7.4V Li-ion cell with a specific float voltage ceiling. This replacement matches that voltage profile, so the controller recognises the new cell and enters its normal trickle charge cycle without triggering a fault state.
- Bench tested on actual hardware: We ran this cell through a full charge cycle and a simulated mains-failure test. The BMS held the discharge curve flat across the load draw and cut off cleanly at the low-voltage threshold without nuisance tripping.
- First-cycle test requirement: Within 24 hours of installation, hold the test button for the full rated duration. This confirms the cell accepts load and lets the charge controller register the new cell before the next scheduled compliance inspection.
Charge indicator staying red after new battery installation
A cell that has been in storage for several months will sit below the float acceptance window the N89 controller uses to confirm a healthy battery. When the incoming voltage reads too low, the controller holds the fault or charging state rather than transitioning to green. Leave the fitting connected to mains for a full 24-hour charge before drawing any conclusions about the cell. If the indicator has not moved to green after 24 hours, check the terminal voltage directly — a healthy charged cell should read between 8.2V and 8.4V at rest.
Emergency light dims partway through a duration test after replacement
Dimming mid-test points to a cell that was not fully conditioned before the test was run. A new Li-ion cell straight from packaging does not always carry a full charge, and the N89 controller may not log enough charge time before the test is triggered. The result is a voltage sag under load that drops below the LED driver's regulation threshold, causing visible dimming. Allow a minimum 24-hour charge on mains after installation, then run the manual test — this gives the cell one complete charge cycle before it faces a full-duration load.