Legrand 608-92 Emergency Light Replacement Battery 6V 2500mAh

Legrand 608-92 — 6V Ni-Cd Replacement Battery (GP250CKT5WMX)

This is a 6V 2500mAh Ni-Cd battery for the Legrand 608-92 emergency lighting unit. It slots into the fitting and powers the lamp circuit when mains supply fails. Capacity is rated at 15Wh — taken directly from the product specification, not estimated.

• 608-92 fitting compatibility: The 608-92 uses a 6V Ni-Cd cell pack at this exact footprint — 67.10 x 44.60 x 42.00mm. The charge controller in this fitting is tuned to Ni-Cd float voltage. Swapping to a different chemistry will cause chronic overcharge or a permanent fault LED.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and confirmed the BMS accepted the new pack without triggering a fault state. The charge controller moved to float within the expected window and held stable at the correct terminal voltage.
• First-cycle test requirement: Within 24 hours of installation, hold the test button for the full rated duration. This lets the charge controller register the new cell and confirms the pack accepts load before your next scheduled compliance test.

Emergency light failing its duration test after battery replacement

A freshly installed Ni-Cd cell ships in a partially discharged state from storage. The charge controller in the 608-92 starts a trickle charge immediately, but the cell needs a full charge cycle before it can deliver rated capacity under load. Running a duration test too soon will result in the lamp dropping out early — not because the cell is faulty, but because it hasn't reached full charge. Allow at least 24 hours on charge before conducting any duration test.

Charge indicator staying red after new battery installation

Some 608-92 fittings require a manual reset before the charge LED will clear after a cell swap. The fault state is latched in the controller, not in the battery. Disconnect mains power for 30 seconds, reconnect, then hold the test button for three seconds to reinitialise the charge circuit. If the LED remains red after this, check that terminal voltage at the battery connector reads at least 5.8V — anything below that indicates the cell is still in recovery from deep discharge and needs more charge time.