Thorn Voyager Solid E3 Replacement Battery 3.6V 2000mAh

Thorn Voyager Solid E3 / E3T — 3.6V Ni-CD Replacement Battery (4681027)

This is a 3.6V, 2000mAh Ni-CD replacement cell for the Thorn Voyager Solid E3 and E3T emergency lighting units. It replaces OEM part 4681027 inside the fitting. Voltage and capacity match the original specification exactly.

• E3 and E3T compatibility: Both the E3 and E3T variants share the same battery bay dimensions and charge controller circuit — 129.20 x 25.00 x 22.50mm cell footprint, 3.6V nominal rail. The charge controller handshake is identical across both builds, so one cell covers both.
• Bench tested on actual hardware: We ran this cell through a full charge cycle on the E3 controller. The charge circuit accepted the cell without fault, brought terminal voltage up to float level, and the green charge LED confirmed acceptance within the expected window.
• First test cycle after installation: Hold the test button for the full rated duration within 24 hours of fitting. This confirms the new cell accepts load current and lets the charge controller register actual cell capacity before any scheduled compliance test is due.

Emergency light failing its duration test after battery replacement

A fresh Ni-CD cell shipped in storage condition holds a partial charge — not a full one. The E3 charge controller applies a trickle charge, but if the fitting is tested before the cell has completed a full charge cycle, available capacity will fall short of the rated duration. Ni-CD chemistry also requires one or two full charge-discharge cycles before the cell reaches its stated 2000mAh capacity. Allow a minimum 24-hour charge period after installation before running a compliance duration test.

Charge indicator not turning green after fitting the new cell

If the cell has self-discharged below roughly 3.0V during storage, the E3 charge controller may not recognise it as a valid cell on first connection. The controller expects terminal voltage within a specific acceptance window before switching to normal charge mode. Leave the fitting connected to mains for two to four hours — the controller's pre-charge stage will bring voltage up into the acceptance range. Once terminal voltage crosses the threshold, the indicator will switch to green and normal charging resumes.