Intec IMT-3500D Replacement Battery 6V 5000mAh Ni-MH

Intec IMT-3500D / ESR8EE5920 — 6V 5000mAh Ni-MH Replacement Battery

This is a 6V 5000mAh Ni-MH replacement battery for the Intec IMT-3500D and ESR8EE5920 handheld flashlights. It slots in where the original pack has degraded and can no longer hold a usable charge. Capacity figure is taken directly from product data at 30Wh.

• IMT-3500D and ESR8EE5920 compatibility: Both models run the same 6V rail and share an identical multi-cell Ni-MH pack format. The cell count, connector, and voltage cutoff threshold match across both units, so one pack covers both.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge on the IMT-3500D driver. The driver accepted charge termination normally, and output held steady across high-draw mode until the protection threshold was reached.
• Multi-cell replacement tip: This pack is a pre-assembled multi-cell unit. Never mix it with a partially used cell from the original pack. If any individual cell inside the old pack has drifted low, pairing old and new cells forces the weaker cell to discharge first under high-current draw, which can damage it permanently.

High-powered flashlight dimming before the battery indicator shows low

The IMT-3500D driver uses brownout protection to step down output when cell voltage dips under load — even if the resting voltage still reads healthy. Ni-MH cells show a flat discharge curve, so the indicator may lag behind actual available capacity. Under high-current draw, internal resistance causes a momentary voltage sag that triggers the driver's step-down before the indicator catches up. If the light recovers brightness after switching to a lower mode, that confirms brownout protection is active, not a faulty battery.

Flashlight cycling through modes or flickering at end of charge

Mode-cycling near the end of a charge cycle is a driver brownout loop — the driver steps down, voltage briefly recovers, output steps back up, then sags again. This repeats until the cell voltage drops below the cutoff floor. The fix is straightforward: switch the flashlight to a lower output mode when cycling starts. This reduces current draw enough to stabilise the voltage above the brownout threshold and lets you extract the remaining usable charge without the light cutting in and out.