About this replacement
Bang & Olufsen Beosound 2 — 3.7V Li-Polymer Replacement Battery (PA-BO12)
This is a 3.7V, 720mAh lithium-polymer cell for the Bang & Olufsen Beosound 2 wireless speaker. It replaces OEM part PA-BO12, the original flat-pack cell that powers the Beosound 2's audio and Bluetooth circuitry. When the original cell can no longer hold a charge after repeated cycles, this is the direct swap.
- Beosound 2 fit: The Beosound 2 uses a single Li-Polymer cell at 3.7V nominal. The PA-BO12 format — 49.00 × 29.90 × 5.00mm — matches the original cell envelope and connector pinout. No adapter, no modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Beosound 2 platform. The protection circuit triggered correctly at low-voltage cutoff, and charge acceptance from empty to full behaved within spec across multiple cycles.
- First-cycle behaviour on the Beosound 2: Run the speaker until it shuts off on the first charge cycle, then charge it fully before use. The Beosound 2's internal monitoring needs one complete cycle to calibrate its charge display against the new cell's actual capacity.
Why the Beosound 2 cuts out at low volume on a new battery
A freshly installed Li-Polymer cell often arrives at storage voltage — around 3.6–3.7V — not full charge. The Beosound 2 draws a combined load from the amplifier and Bluetooth radio. At storage voltage, that combined draw can trip the cell's protection circuit before the speaker plays long enough to complete a charge cycle. Run the speaker down completely on first use, then charge uninterrupted to full. After one complete cycle, cutoff behaviour normalises.
Charge indicator stuck at full but speaker shuts off quickly
This happens when the Beosound 2 reads the new cell's open-circuit voltage and maps it incorrectly to a full-charge state. The cell hasn't been calibrated to the device yet, so the indicator is reading voltage, not true capacity. One full discharge followed by a full uninterrupted charge resets this. After that cycle, the charge indicator tracks the actual cell state accurately.