Bose Sport Earbuds Charging Case Compatible Battery 3.7V 500mAh

Bose Sport Earbuds Charging Base — 3.7V Li-Polymer Replacement Battery (AHB572535)

This 3.7V, 500mAh Li-Polymer cell replaces the internal battery inside the Bose Sport Earbuds Charging Base. It powers the case's charging circuitry, keeping the earbuds topped up between uses. When the original cell degrades, the case loses its ability to hold a charge — this battery restores that function.

• Sport Earbuds Charging Base fit: The AHB572535 matches the voltage rail and physical footprint of the original cell. At 37.30 x 24.80 x 6.00mm, it seats correctly in the base's battery bay without stressing the flex connector or housing tabs.
• Bench tested on actual hardware: We ran this cell through the Sport Earbuds Charging Base and confirmed the BMS accepted the new pack without error. The case began passing charge to the earbuds immediately after the first full cycle completed.
• First-cycle protocol for the charging case: Place the empty earbuds in the case and connect the case to USB power immediately after installing this battery. Let the full sequence run to completion — the case BMS logs the new cell's capacity on that first pass, and the charge indicator will read accurately from that point forward.

Why the charging case shows full but the earbuds cut out after short use

A degraded original cell often sits at storage voltage — roughly 3.6–3.7V — which the case BMS reads as a full charge. Under actual load, that cell collapses quickly because available capacity has fallen far below the rated 500mAh. Replacing the cell resets this. After one complete charge-discharge cycle with the new AHB572535, the BMS re-calibrates its state-of-charge estimate and the case LED will reflect actual capacity accurately.

Charging base not passing power to the earbuds after battery swap

If the case powers on but the earbuds show no incoming charge, the BMS handshake between the new cell and the case controller has not completed. This happens when the replacement cell arrives at a low resting voltage after shipping. Connect the case to USB power for at least 90 minutes before placing the earbuds inside — the BMS needs to bring the cell above 3.75V before it enables the earbud charge rails. If the case LED flashes amber repeatedly, disconnect USB, wait 30 seconds, then reconnect to trigger a fresh BMS initialisation cycle.