Bang & Olufsen Beoplay E8 Compatible Battery 3.7V 500mAh

Bang & Olufsen Beoplay E8 — 3.7V Li-Polymer Replacement Battery (AEC643333A)

This 3.7V, 500mAh Li-Polymer cell replaces the internal battery in the Bang & Olufsen Beoplay E8 true wireless earbud. It fits one earbud unit and the Beoplay E8 TWS charging case. Use it when the original cell has degraded or failed completely.

• Beoplay E8 and E8 TWS Case fit: Both the earbud and the TWS case share the same 3.7V cell footprint and connector spec. The AEC643333A slots into either without modification. Voltage rail and BMS handshake requirements are identical across both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the E8 platform. The BMS accepted the new pack without fault codes, held voltage through audio playback, and stepped down cleanly at the low-voltage cutoff threshold.
• First-cycle charging in the TWS case: After fitting, seat the earbud in the TWS case and run a full charge cycle before use. The E8 case calibrates the cell state-of-charge reading on the first full cycle — skipping this leaves the battery indicator inaccurate until the cycle completes.

Voltage sag under combined Bluetooth and audio draw in the E8

The Beoplay E8 runs Bluetooth transmission and audio processing simultaneously from a single 500mAh cell in a very small housing. That combined draw can pull cell voltage below the BMS protection threshold faster than audio-only devices. A degraded or deeply discharged cell hits this threshold quickly, causing unexpected cutoff. A fresh cell at full capacity handles the combined load without tripping the cutoff.

Battery indicator showing full charge but earbud cuts off after short use

This happens when a new cell is installed at storage voltage — typically around 3.6–3.7V — and the case has not run a calibration cycle yet. The indicator reads the resting voltage as full, but actual usable capacity is not confirmed until the first complete charge-discharge cycle. Seat the earbud in the TWS case, charge to 100%, then use it until the earbud powers off naturally. After that single cycle, the indicator and available capacity will align correctly.