Dual-Lite EV2D Emergency Light Replacement Battery 2.4V 2000mAh

Dual-Lite EV2D Series — 2.4V Ni-MH Replacement Battery (784H69)

This is a 2.4V 2000mAh Ni-MH replacement battery for the Dual-Lite EV2D, EV2DI, EV2DI-24K, and EV4D emergency lighting units. It slots into the battery compartment of these commercial emergency lighting fixtures and restores the backup power function required for building safety code compliance. Capacity is 4.8Wh, matching the original cell specification.

• EV2D and EV4D platform compatibility: These models share the same 2.4V two-cell NiMH configuration, connector pitch, and charge controller float voltage. The same cell pack works across the series because the onboard charge circuit targets the same 2.8–2.9V float range and uses the same thermistor-based overcharge cutoff.
• Bench tested on actual hardware: We ran this cell through charge acceptance, float stabilisation, and load discharge on the EV2D charge board. The BMS accepted the new cell without fault flagging, and float voltage settled within spec at the controller output terminals.
• Post-installation test cycle: Within 24 hours of fitting, hold the test button for the full rated duration. This forces a complete discharge-recharge cycle, allowing the charge controller to register the new cell's capacity before any scheduled compliance inspection.

Emergency light failing its duration test after battery replacement

A freshly installed NiMH cell ships in a partially discharged state. The charge controller needs one full cycle to calibrate to the new cell's capacity curve. Until that cycle completes, the cell may not deliver full rated capacity under load, causing the light to drop out before the test duration ends. Run one complete manual test cycle — full discharge under load, then a full 24-hour recharge — before any compliance test.

Charge indicator staying red after confirmed good installation

Some EV2D units latch a fault condition in the charge controller when the battery is disconnected, even briefly. After fitting the new cell, the controller may still hold the fault state regardless of actual cell voltage. On most EV2D fittings, a manual reset is required — disconnect mains power for 30 seconds, then reconnect. This forces the controller to re-read cell voltage from rest and clear the latched fault flag.