About this replacement
Bang & Olufsen BeoLit 15 / BeoPlay A2 Series — 7.4V Li-ion Replacement Battery (J406/ICR18650NH-2S)
This is a 7.4V, 3400mAh Li-ion replacement battery for the Bang & Olufsen BeoLit 15, BeoLit 17, BeoPlay A2, and BeoPlay A2 Active portable speakers. It replaces OEM part J406/ICR18650NH-2S and restores wireless audio playback when the original pack can no longer hold a charge. Capacity is 25.16Wh — matched to the original cell specification.
- BeoLit 15, BeoLit 17, BeoPlay A2, and A2 Active: All four models share the same 7.4V two-cell series configuration, identical connector pinout, and BMS handshake protocol — which is why one pack covers the full lineup without modification.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the BeoPlay A2 Active. The BMS accepted the cell without fault codes, balanced both cells correctly, and held voltage under combined amplifier and Bluetooth radio draw at high output levels.
- Fuel gauge calibration for daily-use speakers: If you charge the BeoLit before it drops below 50%, do a full discharge to under 20% at least once a month. Constant shallow top-off charging causes fuel gauge drift — the speaker reports incorrect charge levels and the BMS cutoff behaviour becomes unpredictable over time.
Audio distorting before the battery indicator reaches empty
The BeoLit and BeoPlay A2 amplifier stages draw a sharp current spike when driving bass-heavy audio at high volume. As the pack discharges below roughly 7.0V under load, the amplifier can no longer maintain clean headroom and begins clipping — producing audible distortion before the battery indicator shows low. This is a voltage sag issue, not a speaker fault. A fresh cell at full charge holds above 8.0V under the same load and the distortion disappears.
Speaker warm to touch in fabric housing during extended play
The BeoLit 15 and BeoPlay A2 use a fabric-wrapped enclosure that traps heat from both the Class D amplifier and the discharging Li-ion cells. During extended high-volume sessions, the pack surface can reach temperatures that trigger the BMS thermal protection, causing unexpected shutdowns. This is not a battery defect — it is the housing acting as an insulator. Allow 10–15 minutes of idle cooling between long listening sessions, and keep the speaker off soft surfaces like beds or couches that further restrict airflow around the base.