About this replacement
Saft 805565 Series — 2.4V Ni-CD Replacement Battery (MGN0435)
This is a 2.4V, 2000mAh Ni-CD replacement cell for Saft emergency lighting units. It fits models 805565, 135869, 134891, and 786896 — a range of exit signs and backup lighting fixtures that share the same cell format and charge controller interface. Swap it in when the original cell can no longer hold enough charge to pass a duration test.
- Cross-model fit — 805565, 135869, 134891, 786896: These fittings use the same 2.4V two-cell NiCd pack format with identical terminal orientation and charge float voltage. The BMS in each accepts the same current input, so one cell type serves all four model numbers without modification.
- Bench tested on actual hardware: We ran this cell through a full charge cycle and load test on compatible Saft hardware. The charge controller accepted the cell, moved from bulk to float charge without fault, and the cell held voltage under load through a simulated duration draw.
- First-cycle activation on emergency fittings: Hold the test button for the full rated duration within 24 hours of installation. This forces the charge controller to register the new cell's capacity and confirms the cell accepts load before your next scheduled compliance test.
Emergency light failing its duration test after battery replacement
A freshly installed NiCd cell ships in a partially discharged state after months in storage. The charge controller in these Saft fittings starts at a float rate, not a fast charge, so the cell may not reach full capacity for 24 to 48 hours after installation. Running a duration test too soon means the cell runs out of charge before the rated period ends — not a faulty cell, just an uncharged one. Let the fitting charge for a full 24 hours, then run the manual test cycle before logging any compliance result.
Charge indicator staying red after new cell installation
The charge controller monitors incoming cell voltage at power-up to decide whether to begin charging. A cell that has self-discharged below the controller's acceptance threshold during storage can register as a fault rather than a new cell. On most Saft fittings, remove mains power for 10 seconds, reapply, and the controller resamples cell voltage from zero. If the cell is above roughly 1.8V total, the controller will accept it and the indicator will shift to amber then green within the first charge cycle.