Divoom Fairy-OK Replacement Battery 3.7V 350mAh AHB601735P

Divoom Fairy-OK / DitooMic Wireless Microphone — 3.7V Li-Polymer Replacement Battery (AHB601735P)

This 3.7V 350mAh Li-Polymer cell replaces part number AHB601735P in the Divoom Fairy-OK and DitooMic wireless microphone units. It fits the compact internal cavity at 36.70 × 16.60 × 6.80mm and reconnects to the existing BMS board without modification. Capacity figures come from the product data — 350mAh, 1.3Wh.

• Fairy-OK and DitooMic shared platform: Both microphone units run the same 3.7V Li-Polymer cell on the same BMS footprint with the same connector orientation. The AHB601735P part number covers both devices — the BMS handshake, charge threshold, and cutoff voltage are identical across the two.
• Bench tested on actual hardware: We cycled this cell through charge and full-draw discharge on the bench, confirming the BMS holds cutoff at the correct low-voltage threshold and the protection circuit trips cleanly under overcurrent before the cell is stressed.
• Fuel gauge reset after swap: After installing this cell in either MIC unit, run the battery down to the low-battery warning indicator before the first recharge. Skipping this step causes the fuel gauge to read inaccurate charge levels from the first cycle, which compounds into misleading battery indicators over time.

Why the Fairy-OK reads full charge but audio fades out during extended sessions

A 350mAh Li-Polymer cell that has been shallow-cycled — charged back to full before dropping below 50% — loses effective capacity faster than the voltage curve shows. The cell voltage stays above the BMS cutoff point, so the device never reports low battery. But actual charge delivered per cycle shrinks, so audio output drops as the amplifier rail sags. Replacing the cell restores full capacity, but the fuel gauge will remain miscalibrated until you complete one full discharge-to-warning followed by a full charge.

Audio distorting while the battery indicator still shows charge remaining

This happens when a degraded cell can no longer sustain voltage under the combined draw of the Bluetooth radio and the audio amplifier at moderate-to-loud output. Voltage sags below the amplifier's clean operating range before the BMS low-voltage cutoff triggers, so the device stays on but the audio clips. The indicator still shows partial charge because cell voltage recovers the moment current draw drops. Fitting a fresh AHB601735P cell eliminates the sag — verify by charging fully to 4.2V before first use.