Bang & Olufsen BeoPlay A1 2nd Gen C406C2 Replacement Battery 7.4V 3400mAh

Bang & Olufsen BeoPlay A1 2nd Gen — 7.4V Li-ion Replacement Battery (C406C2)

This is a 7.4V, 3400mAh (25.16Wh) Li-ion replacement battery for the Bang & Olufsen BeoPlay A1 2nd Gen portable Bluetooth speaker. It replaces OEM part number C406C2. When the original cell degrades and playtime drops noticeably, this swap restores the pack to full capacity.

• BeoPlay A1 2nd Gen fit: The A1 2nd Gen uses a specific cell configuration tied to its BMS voltage thresholds and physical connector orientation. This replacement matches the 7.4V nominal rail and connector pinout the speaker's charge controller expects.
• Bench tested on actual hardware: We cycled this battery through charge and discharge on a BeoPlay A1 2nd Gen unit. The BMS accepted the pack without error flags, and the fuel gauge reported correctly across the full voltage range from 8.4V fully charged down to the low-voltage cutoff.
• Monthly full-discharge cycle: If the A1 2nd Gen sits on a desk and gets topped off before dropping below 50%, the fuel gauge drifts and the speaker will cut off earlier than the indicator suggests. Run the battery down below 20% at least once a month before recharging to keep the gauge calibrated.

Audio distorting before the battery indicator reaches empty

The BeoPlay A1 2nd Gen amplifier draws a sharp current spike at high volume. As cell voltage sags under that load, the amplifier hits its minimum supply voltage before the fuel gauge registers low battery. The result is audible clipping or distortion while the LED still shows charge remaining. If this happens consistently at loud volumes, check that the cell voltage at rest is above 7.0V — a resting voltage below that points to a degraded or deeply discharged cell that needs replacement.

Speaker won't wake from USB-C after sitting unused for weeks

Li-ion cells self-discharge during storage, and if the BeoPlay A1 2nd Gen sits long enough, the cell voltage can drop below the USB-C PD minimum acceptance threshold. The charge controller won't negotiate a charging contract at that voltage, so the speaker appears completely dead. Connect it to a 5V USB-A charger first — lower voltage sources can trickle charge a deeply discharged cell back above the threshold. Once the cell recovers to around 3.0V per cell, switch to the standard USB-C charger to complete the charge cycle.