Emergi-Lite BL93NC487 4.8V Replacement Battery 1500mAh

Emergi-Lite BL93NC487 — 4.8V Ni-MH Replacement Battery

This is the 4.8V, 1500mAh Ni-MH replacement cell for Emergi-Lite emergency lighting units using part number BL93NC487. It fits emergency exit lights and backup lighting fixtures that switch on automatically when mains power fails. Voltage and chemistry match the original cell exactly so the onboard charge controller recognises it without modification.

• Emergency lighting charge circuit compatibility: Emergi-Lite fittings use a float-charge controller tuned to the voltage window of a 4.8V Ni-MH pack. Swapping to a different voltage or chemistry causes the controller to reject the cell or overcharge it. This replacement stays within that acceptance window.
• Bench tested on actual hardware: We cycled this cell through a full charge and load-discharge sequence. The BMS accepted charge normally, cell temperature stayed within spec, and voltage held stable under load without triggering the low-voltage cutoff prematurely.
• First installation test cycle: Press and hold the test button within 24 hours of fitting this battery. Run it for the full rated duration. This forces one complete charge-discharge cycle, allowing the charge controller to register the new cell's capacity before your next scheduled compliance test.

Charge indicator staying red after new battery installation

A Ni-MH cell sitting in storage for months arrives with a resting voltage below the float-charge acceptance threshold of the fitting's controller. When the controller reads that low voltage, it flags a fault instead of entering normal charge mode. This is not a faulty cell — it needs time. Leave the fitting on mains power for 24 to 48 hours and the cell voltage will climb into the acceptance window, triggering a green indicator. If the LED stays red beyond 48 hours, check the cell voltage directly — it should read at or above 4.0V at rest.

Emergency light dims noticeably partway through a duration test

Dimming mid-test means the cell ran out of usable charge before the rated duration elapsed. On a freshly installed replacement, this almost always means the cell had not completed a full conditioning cycle before the test was triggered. A Ni-MH pack does not reach rated capacity on its first partial charge — it needs at least one full charge before a load test is valid. Charge the fitting on mains for a full 24 hours, then repeat the duration test. Cell voltage at end of test should not drop below 4.0V under load.