RP-Technik NIMHHT4820Q Replacement Battery 4.8V 2000mAh

RP-Technik NIMHHT4820Q — 4.8V Ni-MH Replacement Battery

This is a 4.8V 2000mAh Ni-MH replacement cell for RP-Technik emergency lighting units specified under the NIMHHT4820Q designation. It fits emergency exit signs, evacuation luminaires, and backup lighting fixtures that switch to battery power on mains failure. Voltage and capacity match the original cell exactly.

• NIMHHT4820Q platform fit: RP-Technik emergency fittings in this series use a 4.8V Ni-MH pack wired to a trickle-charge controller that expects a specific float voltage range. Swapping to a different voltage or chemistry causes the charge controller to misread cell state and either overcharge or refuse to charge at all.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a compatible fitting. The charge controller accepted the cell without fault, the float voltage stabilised within the expected window, and the BMS handed off cleanly to standby.
• First test cycle 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 capacity before your next scheduled compliance check.

Emergency light failing its duration test after battery replacement

A freshly installed Ni-MH cell that has been in storage will not deliver its full rated capacity on the first activation. The cell needs one complete charge-discharge cycle to reach the 2000mAh figure. If you run a compliance test immediately after fitting and the light cuts out early, that is a conditioning issue, not a faulty battery. Charge the fitting for a full 24 hours, then repeat the duration test at full load.

Charge indicator staying red after confirmed good installation

A new cell arriving from storage can sit at a resting voltage outside the float acceptance window the charge controller expects. When this happens, the controller reads the cell as faulty and holds the fault or red-charge LED on. The fix is to leave the fitting powered on mains for 24 hours — the controller's trickle stage will bring the cell into range and the indicator should shift to green once float voltage is reached. If the red LED persists beyond 48 hours, check the cell connector seating and confirm no pins are bent.