About this replacement
BAES OVA TD210331 — 3.6V Ni-CD Replacement Battery (329055240)
This is a 3.6V, 2500mAh Ni-CD cell for the BAES OVA TD210331 emergency lighting unit. It fits directly into the fitting housing and connects to the onboard charge controller. Capacity is 9Wh, matching the original cell specification.
- OVA TD210331 fitting compatibility: The TD210331 charge controller floats at 3.6V and draws trickle current through a fixed resistor. This cell matches that voltage rail and accepts the trickle charge rate without triggering the overcharge cutoff that a higher-capacity cell might cause.
- Bench tested on actual hardware: We ran this cell through a full charge cycle and a load discharge on the bench. The BMS registered charge acceptance within the expected window and the cell voltage held above the controller's low-voltage cutoff throughout the discharge phase.
- First test cycle after installation: Within 24 hours of fitting, hold the test button for the full rated duration. This confirms the new cell accepts load under real conditions and allows the charge controller to register cell capacity before the next scheduled compliance inspection.
Charge indicator staying red after new battery installation in the TD210331
A freshly installed Ni-CD cell that has been in storage will often sit below the charge controller's float acceptance window. The TD210331 controller reads this as a fault state and holds the red LED rather than switching to green. The cell needs several hours on trickle charge before its open-circuit voltage rises into the acceptance band. If the LED has not switched to green after 24 hours of mains power, check the float voltage at the battery terminals — it should read between 4.1V and 4.4V.
Emergency light dims and cuts out partway through a duration test
This symptom points to a cell that has not completed a full conditioning charge before the test was run. Ni-CD cells that ship partially discharged do not deliver rated capacity on the first activation — the charge controller needs a full uninterrupted charge cycle to fill the cell properly. Running a duration test too soon after installation drains the partial charge quickly, causing the lamp to dim as voltage sags below the driver threshold. Allow a full 24-hour charge on mains power, then repeat the test from the beginning.