PowerSonic A150321 Emergency Light Replacement Battery 4.8V 2000mAh

PowerSonic A150321 — 4.8V Ni-MH Replacement Battery

This is a 4.8V, 2000mAh Ni-MH replacement battery for emergency lighting fixtures using the A150321 cell. It fits emergency exit signs and backup lighting units that switch to battery power when mains electricity fails. Swap this cell when the original degrades and the fitting can no longer hold a sufficient charge for compliance testing.

• A150321 emergency lighting platform: These fittings run a 4.8V Ni-MH cell because the charge controller is calibrated to the voltage curve and charge acceptance behaviour of that chemistry. Swapping to a different chemistry or voltage will cause the controller to misread state-of-charge and fail to deliver rated output during a mains-loss event.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and simulated mains-loss activation. The BMS accepted the cell without fault, and the fitting cycled through to load output as expected. Charge indicator progressed normally from red to green.
• First test cycle after installation: Within 24 hours of fitting this cell, 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 test.

Charge indicator staying red after new battery installation

Ni-MH cells lose voltage during storage. If a replacement cell arrives with a resting voltage significantly below the float threshold, the charge controller in some A150321 fittings will not enter normal charge mode and the indicator stays red. This is not a fault with the cell or the fitting — the controller is rejecting a voltage it reads as outside the acceptance window. Leave the fitting connected to mains for 12–24 hours. Most controllers will detect the gradual cell recovery and transition into normal float charging, shifting the indicator to green.

Emergency light failing its duration test after battery replacement

A freshly installed Ni-MH cell has not yet gone through a full charge-discharge conditioning cycle, so its usable capacity on day one is lower than rated. If a duration test is run immediately after replacement, the fitting may cut out before the required period ends. This does not mean the cell is faulty. Allow at least one full 24-hour charge before conducting any formal compliance test, then run the manual test button for the complete rated duration to condition the cell properly.