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

Lite-Plan HRN/4-K — 4.8V Ni-CD Replacement Battery (4VTD70 787296)

This is a 4.8V, 4000mAh Ni-CD replacement battery for the Lite-Plan HRN/4-K emergency lighting unit. It slots into the fitting that powers emergency exit signs and backup luminaires during mains failure. Voltage and cell count match the original pack exactly.

• HRN/4-K fitting compatibility: The HRN/4-K charge controller is calibrated to a 4.8V Ni-CD cell string. Swapping chemistry or voltage shifts the float charge point, which trips the fault LED and prevents the cell from reaching full capacity. This pack uses the correct cell count and chemistry so the controller charges it without modification.
• Bench tested on actual hardware: We ran this pack through a full charge cycle and a timed load test at the rated 4.8V output. The BMS held voltage under load without drop-off, and the charge controller moved from red to green within the expected window after a complete conditioning cycle.
• First-install test cycle: Hold the test button for the full rated duration within 24 hours of installation. Ni-CD cells shipped in a partially discharged state need one complete load cycle before the charge controller can accurately register cell capacity — skipping this step risks a failed compliance test at your next scheduled inspection.

Charge indicator staying red after new battery installation

The HRN/4-K charge controller checks cell voltage before entering float mode. A new Ni-CD pack sitting in storage can drop below the acceptance window — typically under 4.2V — which the controller reads as a fault rather than a dischargeable cell. In most cases the controller will not switch to green until the cell voltage climbs past its lower detection threshold. Leave the fitting on mains power for at least 12 to 24 hours; if the indicator stays red beyond 48 hours, measure cell voltage directly — it should read above 4.5V before the controller accepts it.

Emergency light dims and cuts out partway through a duration test

This symptom points to a cell that has not yet reached full rated capacity, not a faulty pack. Ni-CD cells undergo a charge-acceptance process over the first full cycle — pulling the cell hard under load before that cycle completes causes voltage to sag early and the fitting to shut off to protect the circuit. The fix is straightforward: recharge the pack fully on mains power for 24 hours, then re-run the duration test from a confirmed full charge. If the cell still dims within the first portion of the test after two full conditioning cycles, check cell voltage under load — it should hold above 4.2V through the test.