About this replacement
Philips Bodine BSL310SB — 9.6V Ni-Cd Replacement Battery (40000503)
This is a 9.6V, 3000mAh Ni-Cd replacement battery for the Philips Bodine BSL310SB emergency lighting unit. It replaces OEM part numbers 40000503 and 8-KRHT26/51. When the original cell degrades, this restores the unit's ability to power emergency exit lighting during a mains failure.
- BSL310SB platform fit: The BSL310SB uses a nine-cell Ni-Cd pack running a 9.6V nominal rail. The connector pinout, cell count, and BMS charge acceptance window all match the original pack — no modification needed to seat and connect the replacement.
- Bench tested on actual hardware: We ran this cell through a simulated mains-drop test on the BSL310SB. The charge controller accepted the pack without fault codes, the load transfer was immediate, and the BMS held stable across the full discharge curve at rated capacity.
- First test cycle after installation: Within 24 hours of fitting, hold the test button for the unit's full rated duration. This lets the charge controller register the new cell's capacity and confirms the pack accepts load before your next scheduled compliance inspection.
Emergency light failing its duration test after battery replacement
A freshly installed Ni-Cd pack ships partially discharged from storage. The BSL310SB's charge controller needs a full conditioning cycle — typically 24 hours on float charge — before the cell reaches rated capacity. Running a duration test before that cycle completes will cause the light to drop out early. This is not a fault with the fitting or the cell. Allow a full charge, then rerun the test; the unit should hold for the complete rated period.
Charge indicator staying red after new battery installation
The BSL310SB's charge controller checks cell voltage before entering float mode. A replacement pack fresh from storage can sit below the float acceptance window — typically under 9.0V resting — which keeps the fault LED red. The controller is not broken; it is waiting for the cell to climb into range under trickle charge. Leave the unit powered on mains for 12–24 hours. Once cell voltage rises above approximately 9.2V, the indicator should shift to green and normal float charging resumes.