Denon RC-8000 Replacement Battery 4.8V 600mAh Ni-MH

Denon RC-8000 — 4.8V Ni-MH Replacement Battery (3940052005)

This is a 4.8V 600mAh Ni-MH rechargeable battery for the Denon RC-8000 infrared remote control. It replaces OEM part 3940052005 and fits the RC-8000 used with Denon AV receivers and home theater components. When the original cells degrade and the remote stops responding consistently, this battery restores normal IR output.

• RC-8000 fit: The RC-8000 uses a four-cell Ni-MH pack at 4.8V to drive the IR LED array. That voltage rail is fixed by the remote's IR driver circuit — a standard alkaline swap won't work here. This pack matches the connector, cell count, and voltage the remote's PCB expects.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on a Ni-MH capable charger. The BMS held cell balance across all four cells, and IR output measured at the LED remained consistent through discharge to the 4.0V cutoff threshold.
• Ni-MH self-discharge watch: Ni-MH chemistry loses charge in storage — roughly 1–3% per day at room temperature. If the remote sits unused for weeks, put it on charge for a full cycle before use rather than assuming it failed.

Why the RC-8000 IR signal weakens before the battery is fully dead

The RC-8000's IR LED driver needs a minimum voltage to fire at full output. As Ni-MH cells age, internal resistance climbs — so the pack reads 4.2V at rest but sags to 3.8V under the pulse load of an IR burst. At that sag level, the LED fires weakly or inconsistently. The receiver stops seeing the signal before the pack is technically empty. Replacing the battery pack eliminates the sag because fresh cells have lower internal resistance and hold voltage under load.

Remote does nothing after new battery install

If the RC-8000 shows zero response after fitting a new pack, check connector orientation first — the JST-style connector on this pack has a polarity lock but can be forced in reverse with enough pressure. A reversed connection means no power reaches the PCB. Disconnect, flip the connector, and reconnect. If the remote still does not respond, hold any button and point the LED at a phone camera — a working IR LED appears as a purple-white flash on screen at 4.8V.