Bang & Olufsen BeoPlay P2 Replacement Battery 7.4V 900mAh

Bang & Olufsen BeoPlay P2 — 7.4V Li-Polymer Replacement Battery (C129D2)

This 7.4V, 900mAh Li-Polymer battery replaces the original cell in the Bang & Olufsen BeoPlay P2 portable Bluetooth speaker. It fits directly into the P2's compact housing and restores wireless audio playback when the original pack no longer holds a useful charge. Capacity is 900mAh (6.66Wh), matching the OEM specification for this speaker.

• BeoPlay P2 fit: The P2 uses a single Li-Polymer cell at 7.4V nominal — that voltage rail powers both the Bluetooth radio and the Class D amplifier from one pack. This replacement matches that rail exactly, so the BMS handshake with the charging circuit completes without fault codes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a BeoPlay P2 unit, confirming the BMS accepted the pack, the charge indicator stepped correctly through all states, and the amplifier drew cleanly from the cell without triggering low-voltage cutoff at moderate listening levels.
• Fuel gauge reset after install: After fitting a new cell, run the speaker down until it powers off automatically, then charge uninterrupted to 100% before using it again. Skipping this step leaves the P2's fuel gauge calibrated to the old degraded cell, so the charge indicator will misread the new pack's actual state.

Capacity fade from constant top-off charging on the P2

The BeoPlay P2 is often left on a desk and plugged in after every short listening session — sometimes recharged from 70% or higher. Li-Polymer cells cycled repeatedly in the upper voltage band (above 4.1V per cell) accumulate stress on the cathode faster than cells that run through fuller discharge cycles. Over several months, this pattern cuts usable capacity noticeably even though the pack shows "full." Discharge the speaker below 20% at least once a month before recharging to slow this degradation on the new cell.

Audio distorting before the battery indicator reaches empty

When the P2's cell voltage sags under the amplifier's peak current draw, the amp clips before the BMS triggers its low-voltage cutoff — you hear distortion while the indicator still shows charge remaining. This happens because the BMS cutoff threshold sits below the voltage at which the amplifier loses clean headroom. It is more common at higher volume where instantaneous current demand spikes. If distortion appears consistently before the battery warning, the cell has aged past the point where it can sustain the amplifier's peak draw — replacement brings the pack's internal resistance back down to a level where the amp runs clean.