Bang & Olufsen BeoPlay H4 Replacement Battery 3.7V 600mAh

Bang & Olufsen BeoPlay H4 — 3.7V Li-Polymer Replacement Battery (AHB622540PMT-02)

This 3.7V, 600mAh lithium-polymer cell replaces the original battery in the Bang & Olufsen BeoPlay H4 wireless headphones. It restores audio playback and Bluetooth connectivity when the original cell has degraded or will no longer hold a charge. Dimensions are 42.00 x 25.00 x 6.20mm — verify against your existing cell before fitting.

• BeoPlay H4 fit: The H4 runs a single-cell Li-Polymer pack at 3.7V nominal, feeding the Bluetooth radio and audio amplifier from one shared rail. Any replacement must match the cell footprint and connector orientation exactly — the H4's compact earcup housing leaves no room for error on either dimension.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles monitoring the BMS cutoff thresholds. The protection circuit tripped correctly at low-voltage cutoff and recovered cleanly on re-charge, with no false over-current trips under combined Bluetooth and audio load.
• First-cycle charge on the H4: After fitting, charge the headphones fully via USB before use. The H4's onboard fuel gauge recalibrates its capacity estimate during the first complete charge cycle — skipping this step often causes the headset to report inaccurate battery status for the first several sessions.

Why the BeoPlay H4 cuts out mid-call on a new battery

The H4 draws simultaneously from the Bluetooth radio and the audio amplifier during calls. On a freshly fitted cell sitting at storage voltage, this combined load can pull the cell voltage low enough to trip the BMS under-voltage cutoff — even if the cell is not actually flat. The fix is a full charge before first use, which brings the cell to its rated 3.7V nominal and gives the BMS headroom to handle transient load spikes. After one or two full cycles, this behaviour stops.

Talk time shorter than rated across the first few uses

Li-Polymer cells do not deliver full rated capacity immediately after manufacture or storage. The 600mAh rating reflects capacity after the cell has been through several charge-discharge cycles. On cycles one through three, available capacity typically runs lower than rated as the electrolyte settles and the electrode surfaces condition. Run three to five complete charge and discharge cycles and capacity will stabilise — discharge to the point the headphones shut off naturally, then charge fully to 4.2V before assessing real-world talk time.