Bang & Olufsen BeoPlay P6 Compatible Battery 7.4V 3400mAh

Bang & Olufsen BeoPlay P6 — 7.4V Li-ion Replacement Battery (C129D1)

This is a 7.4V, 3400mAh (25.16Wh) Li-ion replacement battery for the Bang & Olufsen BeoPlay P6 portable Bluetooth speaker. It fits the BeoPlay P6 across all known hardware revisions, including model numbers 11400 and 1140026. Swap it in when the original cell no longer holds enough charge to sustain wireless playback away from a power source.

• BeoPlay P6 / 11400 / 1140026 fitment: These three model references share the same battery bay geometry, connector pinout, and BMS handshake protocol, so a single cell covers all of them. The C129D1 / 2INR19/66 cell spec matches the voltage rail the P6 amplifier board expects.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the P6 platform. The BMS accepted the pack without fault codes, balanced cells correctly at top-of-charge, and applied the low-voltage cutoff at the expected threshold before the amplifier stage starved.
• Monthly discharge cycle for the P6: If the P6 sits on a desk and gets topped off constantly, let it drop below 20% at least once a month before recharging. Continuous shallow cycling causes the fuel gauge IC to drift, making the charge indicator unreliable long before actual capacity loss becomes severe.

Capacity fade from constant top-off charging on the BeoPlay P6

Li-ion cells degrade faster when kept near full charge for extended periods — a pattern that fits desk speakers almost exactly. The P6 has no trickle-discharge circuit to offset this; it just sits at 100% until you unplug it. Over months, this compresses the usable capacity window at the top of each cycle. Running a full discharge once a month before recharging slows that process noticeably.

Audio distorting before the battery indicator reaches empty

This happens when the cell voltage sags under combined amplifier and Bluetooth radio draw before the BMS trips the low-voltage cutoff. The amplifier clips first — you hear distortion — while the charge indicator still shows one or two bars. It is not a speaker fault. It means the cell can no longer sustain the current the amp pulls at moderate-to-high volume. Replacing the battery resolves it; check that the new pack reads at least 7.4V open-circuit before installation.