Schrack NLK1U003SC 4.8V Replacement Battery 600mAh Ni-MH

Schrack NLK1U003SC Series — 4.8V Ni-MH Replacement Battery (NLAKKU4808)

This is a 4.8V, 600mAh Ni-MH replacement battery for Schrack emergency lighting units. It fits the NLK1U003SC, NLK2U003SC, NLK3U003SC, and NLS1D003SC series fittings. It replaces OEM part numbers AW-0480-0080AAA-NM01 and NLAKKU4808.

• NLK and NLS series compatibility: These fittings share the same 4.8V cell configuration, connector pinout, and charge controller voltage window. The battery pack dimensions — 43.60 × 20.80 × 20.80mm — match the original cavity without modification.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and mains-failure simulation. The charge controller accepted the cell within normal float voltage range, the LED transitioned to green, and the lamp activated correctly on simulated mains loss.
• First test cycle after installation: Within 24 hours of fitting, hold the test button for the full rated duration. This allows the charge controller to register the new cell capacity and confirms the cell accepts load before the 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 from storage. The charge controller in these Schrack fittings applies a trickle charge, but the cell needs at least one full 24-hour charge cycle before it reaches rated capacity. Running a duration test too soon will show a shortened illumination period — this is not a faulty cell. Allow a full charge before the first compliance test, and the cell will deliver its rated 600mAh on subsequent checks.

Charge indicator staying red after new battery installation

If the charge LED remains red after fitting, the cell voltage at installation is likely below the float acceptance threshold of the charge controller. Cells held in warehouse storage can self-discharge to a point where the controller flags them as a fault rather than beginning a normal charge. Leave the fitting connected to mains for 12–24 hours — the controller will typically recover the cell once voltage climbs above 4.2V. If the LED has not shifted to green after 24 hours, check the connector seating and confirm terminal contact.