Sharp 51500RS Emergency Light Replacement Battery 6V 2000mAh

Sharp 51500RS / CE140 Series — 6V Ni-MH Replacement Battery

This is a 6V, 2000mAh Ni-MH rechargeable battery for Sharp emergency lighting units. It fits the 51500RS, CE140, and CE140P fittings. These units use this cell to power backup illumination when mains supply fails.

• 51500RS, CE140, and CE140P compatibility: All three fittings run the same 6V charging rail and share a common cell format — 52.38 x 43.46 x 27.20mm. The charge controller on each model expects the same float voltage window, so the same Ni-MH cell works across all three without modification.
• Bench tested on actual hardware: We ran this cell through a charge-discharge cycle on the CE140 platform. The BMS accepted charge without flagging a fault, and the cell held stable voltage under the lamp load through a full simulated duration test.
• First-cycle conditioning on emergency fittings: Hold the test button for the full rated duration within 24 hours of installation. This lets the charge controller register the new cell capacity and ensures the first scheduled compliance test reflects the actual output rather than a partial conditioning state.

Charge indicator staying red after new battery installation

Sharp CE140-series charge controllers check incoming cell voltage before entering float mode. A Ni-MH cell stored for several months can arrive sitting below the acceptance threshold — typically under 5.4V open circuit. The controller sees this as a fault state and holds the red LED rather than switching to green. Leave the fitting powered for 12–24 hours; the trickle input will bring the cell voltage up into the acceptance window and the indicator will switch normally. If the LED stays red past 24 hours, measure cell voltage directly — it should read above 5.8V at that point.

Emergency light dimming partway through a duration test

A new cell that has not completed a full conditioning cycle will hit an early voltage sag under lamp load. This is not a faulty cell — it is a partially charged one. Ni-MH chemistry needs at least one complete charge-discharge cycle to reach rated capacity. Run a full manual test within the first 24 hours to complete that cycle. After a full recharge following that test, the cell should sustain the lamp load at or above 5.4V for the fitting's rated duration.