About this replacement
Thorn Voyager Star — 2.4V Ni-MH Replacement Battery (59004666)
This is a 2.4V, 4000mAh Ni-MH replacement cell for the Thorn Voyager Star emergency lighting unit. It fits the Star series fitting directly, restoring full backup illumination capacity for exit signs and emergency pathway lighting. Voltage and capacity match the original OEM specification (59004666).
- Thorn Voyager Star compatibility: The Star series uses a 2.4V Ni-MH cell on a simple trickle-charge controller. The connector and cell format are fixed to this platform — no BMS handshake is required, but cell voltage on arrival must sit within the controller's float acceptance window for charging to begin correctly.
- Bench tested on actual hardware: We cycled this cell through a full charge and load test. The cell accepted charge cleanly, held voltage under sustained load, and showed no signs of voltage collapse at the end of a full duration draw.
- 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 cell before your next scheduled compliance test — skipping this step risks a failed duration result on the first formal inspection.
Charge indicator staying red after new battery installation
Thorn Voyager Star fittings use a simple voltage-threshold detector to confirm the cell is within charging range. A new Ni-MH cell stored for several months can arrive with a resting voltage low enough that the controller treats it as a fault rather than a discharged cell. The controller will not enter float charge from this state without a brief conditioning input. Connect the fitting to mains and leave it undisturbed for 12–24 hours — the trickle current is usually enough to nudge the cell voltage above the acceptance threshold. If the indicator remains red past 24 hours, verify mains supply to the fitting and confirm cell voltage is reading above 2.0V with a meter at the cell terminals.
Emergency light dims partway through a duration test
This happens when the cell has not completed a full conditioning charge before the test is run. Ni-MH cells do not reach rated capacity on the first partial charge cycle — internal resistance stays elevated and voltage sags under load sooner than expected. The fix is straightforward: allow a minimum 24-hour charge on mains before running any duration test. If dimming still occurs after a full 24-hour charge, check that the trickle charge circuit is delivering current — a failed charge resistor in older fittings will leave the cell only partially charged regardless of how long mains power is applied.