ABM NIMHHT4820Q 4.8V Emergency Light Compatible Battery 2000mAh

ABM AMC003(SC) Series — 4.8V Ni-MH Replacement Battery (NIMHHT4820Q)

This is a 4.8V 2000mAh Ni-MH replacement battery for ABM emergency lighting units. It fits the AMC003(SC), AKD003(SC), AMD008(SC), AXC(W), AXC(D), and 19 additional ABM models sharing the same voltage rail and cell format. Capacity is 2000mAh (9.6Wh) as specified by OEM part NIMHHT4820Q.

• AMC003(SC) and AKD003(SC) series compatibility: These models share the same 4.8V four-cell Ni-MH configuration and charge controller float voltage. The connector and cell pack dimensions (51.00 × 29.50 × 29.50mm) are consistent across all listed fittings, so the BMS handshake on the charge circuit accepts this cell without modification.
• Bench tested on actual hardware: We ran the cell through a full charge cycle and a simulated mains-failure load test. The charge controller accepted the cell within the expected float window, and the BMS held steady voltage without triggering low-cell cutoff under sustained load.
• First-installation test cycle: Within 24 hours of fitting, hold the test button for the full rated duration. This lets the charge controller register the new cell capacity before your next scheduled compliance test — skipping this step is the single most common cause of a failed duration test after a fresh installation.

Charge indicator staying red after new battery installation

A freshly manufactured Ni-MH cell typically ships at a partial state of charge — often below the float acceptance window the ABM charge controller expects to see before switching to green. The controller reads terminal voltage on insertion, and if it falls outside the acceptance band, it holds the fault state rather than beginning a normal charge cycle. Leave the fitting on mains power undisturbed for a full 24-hour charge period. If the indicator has not moved to green after that period, check cell polarity and connector seating — a reversed pack will read as an open circuit and keep the fault LED active indefinitely.

Emergency light failing its duration test after battery replacement

A new Ni-MH cell does not reach rated capacity on its first activation cycle — it typically needs one full charge-discharge conditioning pass to deliver the full 2000mAh. If a compliance duration test is run before that conditioning cycle completes, the light will cut out early and log a failure. Run a manual test immediately after the 24-hour initial charge by pressing and holding the test button through the full rated period. Schedule your formal compliance test only after that first manual cycle is complete.