Acoustic Research ARRX18G Replacement Battery 3.7V 1000mAh

Acoustic Research ARRX18G — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1000mAh lithium-ion battery for the Acoustic Research ARRX18G remote control. It replaces the original internal cell when the remote stops responding or holds no charge. No OEM part number is published for this cell — fit is confirmed by voltage, physical dimensions (53.04 × 35.53 × 7.13mm), and connector type.

• ARRX18G fit confirmation: The ARRX18G uses a single flat Li-ion cell running at 3.7V nominal to power the microcontroller and IR LED array. This cell matches the original voltage rail and physical envelope — both matter in a remote where the battery sits inside a sealed compartment with no flex room.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The protection circuit held cutoff at the expected low-voltage threshold and did not allow charging above 4.2V — both within spec for this form factor.
• Connector orientation on reinstall: The ARRX18G's internal connector is small and easy to reverse. Before seating the plug, confirm the polarity markings on the PCB match the wire colors. A reversed connector will prevent the remote from powering on without causing any visible damage.

Why the ARRX18G goes completely dead before the battery reads empty

Li-ion cells powering IR remotes have a hard low-voltage cutoff built into the protection circuit. On the ARRX18G, the microcontroller needs a stable 3.0V minimum to execute button presses — when the cell drops below that threshold under load, the remote shuts down even if a resting voltage reading still looks acceptable. This is why the remote can appear to die suddenly. A cell showing 3.1V at rest may still collapse below 3.0V the moment the IR LED fires. Replace the cell when the remote becomes intermittent, not after it stops completely.

ARRX18G powers on but buttons stop registering mid-session

This symptom usually means the cell voltage is sagging under the brief current spike the IR LED draws with each button press. The remote's standby draw is low enough that the battery appears fine — but the transmit pulse pulls more current than a degraded cell can deliver cleanly. The result is dropped commands or a remote that works at point-blank range but not at normal distance. Swap the battery and test from two metres before assuming the remote itself has failed.