YUASA 16-552 Emergency Light Replacement Battery 2.4V 8000mAh

YUASA 16-552 / 2DH4-0F4/LS-0B — 2.4V Ni-MH Replacement Battery

This is a 2.4V, 8000mAh Ni-MH replacement cell for YUASA emergency lighting units fitted under references 16-552 and 2DH4-0F4/LS-0B. It restores backup illumination in commercial and residential emergency light fittings that activate on mains failure. Voltage and geometry match the original cell — 121.10 x 33.65 x 33.00mm.

• 16-552 and 2DH4-0F4/LS-0B fitments: Both references share the same 2.4V two-cell Ni-MH configuration and connector orientation. The charge controller in these fittings floats at a fixed voltage rail, so the replacement cell must match nominal voltage exactly to avoid float rejection.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and discharge load test. The BMS accepted charge within normal parameters and the cell held voltage under sustained load without dropping below the low-voltage cutoff threshold.
• First-cycle test after installation: Within 24 hours of fitting, 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 the next scheduled compliance inspection.

Emergency light failing its duration test after battery replacement

A freshly installed Ni-MH cell ships in a partially discharged state after storage. The charge controller needs a full conditioning cycle — typically 24 hours on float charge — before the cell reaches rated capacity. Running a duration test immediately after installation will produce a short result because the cell simply hasn't been fully charged yet. Allow a minimum 24-hour charge period, then rerun the test.

Fitting still showing fault LED after confirmed good installation

Some emergency light fittings latch a fault LED in firmware and will not clear it automatically once the battery is replaced. The fault state persists even when the new cell is seated correctly and charging normally. On most affected fittings, a manual reset is required — press and hold the test button for 10 seconds with mains power applied. If the LED clears, the fitting is functioning correctly and the fault was a latched state, not an ongoing fault.