About this replacement
Legrand 062632 / 660975 — 7.2V Ni-MH Replacement Battery (C400BT)
This is a 7.2V, 4000mAh Ni-MH replacement battery for the Legrand 062632 and 660975 emergency lighting units. It slots into the fitting in place of the original cell pack and supplies the backup power the unit draws during a mains failure or test cycle. Capacity is 4000mAh (28.8Wh), matching the original specification.
- 062632 and 660975 compatibility: Both fittings run the same 7.2V cell pack on the same charge controller circuit with the same connector arrangement. The BMS float voltage and charge termination logic are identical across both models, so one cell pack covers both units without modification.
- Bench tested on actual hardware: We cycled this cell on the 062632 charge circuit and confirmed the BMS accepted charge termination normally, with the charge indicator transitioning from red to green within the expected window after a full conditioning cycle.
- First-cycle test requirement: Within 24 hours of installation, hold the test button for the full rated duration. A cell shipped from storage may sit below the charge controller's float acceptance window. One full test cycle lets the controller register the new cell capacity before your next scheduled compliance inspection.
Emergency light failing its duration test after battery replacement
A freshly installed Ni-MH cell does not arrive at full rated capacity. Storage and transit leave the cell partially discharged, and the charge controller on the 062632 uses a trickle float charge that can take 24 hours or more to bring the cell to full capacity. Running a compliance duration test too soon after installation means the cell starts the test below capacity and drops out early. Allow a minimum 24-hour charge period after installation before running any formal duration test.
Charge indicator staying red after new battery installation
The charge controller on these fittings checks cell voltage at float before accepting the cell as healthy. A cell that has been in storage for several months can sit below 6.0V open circuit — low enough that the controller reads it as a fault rather than a discharged cell. Leave the fitting on mains for at least two hours; the controller will usually begin trickle charging once the cell voltage rises above the fault threshold. If the indicator stays red past four hours, check the connector seating and confirm terminal contact — a partial connection holds the voltage reading low.