BAES OVA Emergency Light Replacement Battery 4.8V 800mAh

BAES OVA Series — 4.8V Ni-CD Replacement Battery (TD512433)

This is a 4.8V, 800mAh nickel-cadmium replacement battery for BAES OVA and OVA 38459 emergency lighting units. It replaces the internal cell pack that powers backup illumination when mains power fails. Voltage and capacity match the original TD512433 specification exactly.

• OVA and OVA 38459 compatibility: Both models run the same 4.8V cell configuration with an identical connector and charge controller interface. The TD512433 cell geometry — 98.70 x 16.90 x 14.60mm across two cells — matches the OEM housing without modification.
• Bench tested on actual hardware: We ran this cell pack through a full charge cycle and simulated a mains-failure event. The charge controller accepted the cell voltage within the expected float window, and the BMS held steady under load without triggering a protection cutoff.
• Post-installation test cycle: Within 24 hours of fitting, hold the test button for the full rated duration. This confirms the new cell accepts load and lets the charge controller register cell capacity before the next scheduled compliance test — skipping this step is the most common reason a new battery fails a duration check.

Charge indicator staying red after new battery installation

BAES OVA charge controllers compare incoming cell voltage against a float acceptance window before switching to green. A fresh Ni-CD cell from storage often sits below this threshold — typically under 4.6V — which keeps the controller in fault state. This is not a defective cell or a wiring fault. Allow a full 24-hour charge from the mains and the indicator will move to green once cell voltage climbs into the acceptance range above 4.8V.

Emergency light dims partway through the duration test

A new Ni-CD cell that has not completed its first conditioning cycle will sag under sustained load before reaching rated capacity. The charge controller has no way to distinguish this from a degraded old cell, so the fitting dims as voltage drops below the cutoff threshold. The fix is straightforward: run one complete charge-then-discharge test cycle before logging compliance results. After that first full cycle, the cell reaches its rated 800mAh and holds output across the full test duration.