Eaton 40071353666 Emergency Light Replacement Battery 3.7V 2600mAh

Eaton GUIDELED EURO X LED AT (40071353666) — 3.7V Li-ion Replacement Battery

This is a 3.7V, 2600mAh (9.62Wh) Li-ion cell for the Eaton GUIDELED EURO X LED AT emergency lighting fitting, model 40071353666. It restores backup illumination in units that have failed their duration test or will no longer hold charge. Fit this cell when the fitting shows a fault LED, fails to activate on mains loss, or the existing cell has visibly swollen.

• GUIDELED EURO X LED AT compatibility: The 40071353666 fitting uses a single-cell Li-ion circuit with a float charge controller matched to 3.7V nominal. Swapping to a cell outside that voltage window causes the controller to reject charge or report a fault. This cell sits within the acceptance window.
• Bench tested on actual hardware: We ran the cell through a full charge cycle and simulated mains-failure activation. The BMS held voltage under sustained LED load without triggering low-voltage cutoff prematurely. Charge controller advanced to green within the expected window.
• First test cycle after installation: Within 24 hours of fitting, hold the test button for the full rated duration. This confirms the cell accepts load and lets the charge controller register actual capacity before the next scheduled compliance inspection.

Charge indicator staying red after new battery installation

A cell shipped from storage can sit at 3.5V or lower — below the float acceptance threshold on the GUIDELED charge controller. When the controller sees that voltage on insertion, it may flag a fault rather than begin a charge cycle. Leave the fitting connected to mains for a full 24-hour period without triggering the test button. Once the cell climbs above the acceptance threshold through trickle input, the indicator should advance to green. If it remains red past 24 hours, measure the cell terminals — you should see at least 3.6V.

Emergency light dims and cuts out partway through a duration test

This is not a faulty cell — it is an unconditioned one. A cell that has not completed one full charge-discharge cycle before a duration test will not deliver rated capacity, and the LED load will pull voltage below the BMS cutoff threshold earlier than expected. Allow a minimum 24-hour charge after installation before running any test. If dimming still occurs after conditioning, measure terminal voltage mid-test — a healthy 3.7V cell should stay above 3.4V through most of the rated duration.