Interstate NIC1158 Emergency Light Replacement Battery 2.4V 2100mAh

Interstate NIC1158 — 2.4V Ni-MH Replacement Battery

This is a 2.4V, 2100mAh Ni-MH replacement cell for the Interstate NIC1158 emergency lighting unit. It slots into emergency light fittings and exit sign systems that use this cell to power backup illumination during a mains failure. Voltage and chemistry must match exactly — the charge controller in these fittings is calibrated for Ni-MH at 2.4V.

• NIC1158 fitting compatibility: Emergency lighting fittings that take this cell share a trickle-charge circuit tuned to Ni-MH float voltage. Swapping in a different chemistry or voltage trips the charge controller into a permanent fault state, so staying with 2.4V Ni-MH is not optional.
• Bench tested on actual hardware: We cycled this cell through a simulated mains-drop test. The BMS accepted the load immediately, and the cell held voltage under the lamp draw without dropping below the fitting's low-voltage cutoff threshold.
• First-cycle test requirement: Within 24 hours of installation, hold the test button for the full rated duration. This lets the charge controller register the new cell's capacity and confirms the cell accepts load before your next scheduled compliance test.

Emergency light failing its duration test after battery replacement

A freshly installed Ni-MH cell ships in a partially discharged state after months in a warehouse. The fitting's trickle charger tops it up slowly — at 2.4V, the charge current is low by design. Until the cell completes at least one full charge-discharge cycle, its usable capacity is below the rated 2100mAh. Running the duration test too early produces a short result that looks like a failed battery but is actually an uncharged one. Allow 24 hours of continuous mains connection before conducting the first compliance test.

Charge indicator staying red after confirmed good installation

Some emergency lighting fittings latch a fault LED in hardware — it does not reset automatically once the fault clears. If the cell voltage sat outside the float acceptance window during storage, the controller logs a fault even after the new cell is installed and charging normally. Check the fitting's manual for a manual reset procedure, which is usually a timed press of the test button. If the LED clears and returns green within a few minutes, the cell is charging correctly and no further action is needed.