About this replacement
BIG BEAM 2SE12N7 / H2SE12N7 — 12V Ni-CD Replacement Battery (N127)
This is a 12V, 8000mAh nickel-cadmium replacement battery for BIG BEAM emergency lighting units, specifically the 2SE12N7 and H2SE12N7 models. It replaces OEM part numbers N127, 126-0874GR, and 783HP7. The battery restores the unit's ability to deliver emergency egress lighting during a mains failure.
- 2SE12N7 and H2SE12N7 compatibility: Both models share the same 12V battery bay, connector pinout, and charge controller circuit. Either unit will accept this cell without modification to the housing or wiring.
- Bench tested on actual hardware: We cycled this cell through a full discharge-recharge sequence on the bench. The charge controller accepted the cell, moved from charge to float, and the test button triggered the load circuit correctly at full rated voltage.
- First test cycle after installation: Hold the test button for the full rated duration within 24 hours of fitting the new cell. This lets the charge controller register the new cell capacity before any scheduled compliance test. A new Ni-CD cell may not deliver full rated output until it has completed at least one full load cycle.
Emergency light failing its duration test after battery replacement
A freshly installed Ni-CD cell often ships in a partially discharged state. The charge controller in the 2SE12N7 begins trickle charging immediately, but it can take up to 24 hours at float to reach full capacity. If a compliance test runs too soon after installation, the cell will not sustain the lamp load for the full rated duration. Allow a full 24-hour charge before running any duration test, then manually trigger the test button to confirm the cell holds voltage under load.
Charge indicator staying red after new battery installation
The charge controller in these units uses the incoming cell voltage to determine charge state. A cell that has been in storage for an extended period may sit below the float acceptance window — typically under 11V — causing the controller to hold in fast-charge mode and keep the indicator red. This is normal behaviour. Leave the unit on mains power for 24 hours; once the cell climbs above approximately 12.0V, the controller will shift to float and the indicator will turn green.