About this replacement
Besam UniTurn — 28.8V Ni-CD Replacement Battery (24SC-2000)
This is a 28.8V, 2000mAh Ni-CD replacement battery for the Besam UniTurn automatic door operator. It fits the UniTurn's motor drive and control circuit, providing backup power to complete door cycles when mains power is interrupted. Capacity is 57.6Wh, matching the OEM part 24SC-2000 specification.
- UniTurn backup power architecture: The UniTurn relies on this battery pack to power both the drive motor and the door controller during a mains failure. The voltage rail and connector configuration match the OEM pack directly — the controller's BMS handshake checks pack voltage at startup before enabling the backup circuit.
- Bench tested on actual hardware: We cycled this pack through simulated mains-fail events and confirmed the BMS correctly enabled the backup circuit, held voltage through a full open-and-close cycle, and released cleanly back to standby charge state once mains were restored.
- Post-installation load test: After installing the battery, manually trigger a power-fail simulation during a low-traffic period. The UniTurn must complete a full door cycle — open, dwell, and close — under real motor load. A successful cycle confirms the pack is charged and the backup circuit is live before the door returns to normal service.
Automatic door not completing full open cycle on battery backup
During a mains failure, the UniTurn controller draws peak current at motor start — this is the highest load the backup battery sees. A Ni-CD pack that has sat in standby without a full charge cycle will sag below the controller's minimum voltage threshold mid-cycle and the door stalls. The fix is not the battery itself but its state of charge: Ni-CD chemistry requires a full 24-hour charge after installation before the first load test. If the door still stalls, check pack voltage under load — it should hold above 24V through the full cycle.
UniTurn losing door programming after a power outage
The UniTurn controller stores door parameters — open force, hold-open timing, and obstacle detection thresholds — in volatile memory backed by the battery. When the backup battery depletes fully, that memory loses power and the controller reverts to factory defaults on the next mains restore. The symptom is a door that re-opens to the wrong width or ignores programmed hold-open timing after an outage. Replace the battery, charge it fully, then re-enter the door parameters via the controller's setup sequence.