Schneider MGN0534 Emergency Light Replacement Battery 3.6V 4000mAh

Schneider TD110333 / OVA58985 — 3.6V Ni-CD Replacement Battery (MGN0534)

This is a 3.6V, 4000mAh nickel-cadmium cell for Schneider emergency lighting units. It fits the TD110333, OVA58985, 130041, 131176, and six additional Schneider emergency lighting models sharing the same charge controller and connector spec. Capacity figure is sourced from product data — 14.4Wh per cell.

• Cross-compatible Schneider emergency lighting range: These models share the same 3.6V charge rail, physical cell footprint (178.60 × 34.00 × 32.70mm), and float charge voltage threshold — which is why one cell covers the full group without wiring changes.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and a timed discharge under rated load. The cell accepted float charge cleanly and the BMS registered capacity without fault codes at the controller.
• First-cycle activation 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 before the next scheduled compliance test — skipping it can cause a false fail on the first duration check.

Emergency light failing its duration test after battery replacement

A freshly installed Ni-CD cell ships at partial charge after months in storage. The charge controller on Schneider emergency fittings uses voltage to estimate capacity, and a low starting voltage can cause it to underestimate what the cell holds. This means the fitting may cut out before the full rated duration on the first test — even though the cell itself is not defective. Run a full 24-hour charge before the first test cycle, then perform a complete manual discharge test to condition the cell and allow the controller to recalibrate its capacity estimate.

Charge indicator staying red after new battery installation

If the fitting shows a permanent red or fault LED after a confirmed correct installation, the cell voltage on arrival may sit outside the float acceptance window the controller expects — typically below 3.2V after extended storage. The controller reads this as a fault condition rather than initiating a charge cycle. Connect mains power and leave the fitting undisturbed for a minimum of 24 hours. If the indicator does not shift to green after a full charge cycle, check whether the fitting requires a manual reset by briefly pressing the test button to clear the stored fault state.