Lite-Plan HRN/4 Emergency Light Replacement Battery 4.8V 4000mAh

Lite-Plan HRN/4 Series — 4.8V Ni-CD Replacement Battery (3409)

This is a 4.8V, 4000mAh nickel-cadmium battery for the Lite-Plan HRN/4 and HRN/4-K emergency lighting units. It replaces OEM part numbers 3409, 621-0792, and 4 VTD 70 787296. The cell physically measures 130 × 62 × 32.90mm and slots directly into the existing battery bay.

• HRN/4 and HRN/4-K compatibility: Both fittings share the same charge controller circuit and battery bay dimensions. The 4.8V nominal voltage matches the float charge rail on both variants, so the existing charge board does not need modification.
• Bench tested on actual hardware: We cycled this cell through full charge and load discharge on a Ni-CD compatible tester. The BMS accepted charge without thermal event, and the cell held voltage under simulated emergency load without dropping below the fitting's low-voltage cutoff threshold.
• First-cycle commissioning on emergency fittings: 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 capacity before any scheduled compliance test runs against it.

Charge indicator staying red after new battery installation

Ni-CD cells lose charge during storage, so a replacement cell often arrives below the charge controller's float acceptance window. The controller reads the low resting voltage as a fault condition and holds the fault state rather than entering normal charge mode. Leave the fitting connected to mains for a full 24-hour charge cycle before expecting the indicator to shift to green. If the LED stays red beyond 48 hours, measure the cell terminal voltage — it should read at least 5.4V fully charged at 4.8V nominal.

Emergency light dims partway through a duration test

A cell that has not completed at least one full conditioning cycle will not deliver its rated 4000mAh on the first test. The fitting draws steady current from a cell that has not yet reached full electrochemical capacity, and voltage sags early under load. This is not a faulty cell — it is an unconditioned one. Run the test button cycle once immediately after installation, allow a full 24-hour recharge, then run the formal compliance duration test as a second cycle.