Harman/Kardon GO + Play 3 Replacement Battery 10.8V 2600mAh

Harman/Kardon GO + Play 3 — 10.8V Li-ion Replacement Battery (C1146B-18650-3S1P)

This is a 10.8V, 2600mAh (28.08Wh) Li-ion replacement battery for the Harman/Kardon GO + Play 3 portable Bluetooth speaker. It fits the GO + Play 3 directly, restoring wireless audio capability when the original cell no longer holds a usable charge. Voltage and cell format match the original 3S1P 18650 configuration.

• GO + Play 3 cell configuration: The GO + Play 3 runs a 3-cell series pack (3S1P, three 18650 cells in series) to hit the 10.8V nominal rail. The speaker's internal power board expects that voltage for both the Class D amplifier and Bluetooth module — a two-cell or four-cell pack will not satisfy the BMS handshake or the amplifier's supply requirements.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the GO + Play 3 board. The BMS accepted the cell, balanced correctly across all three cells, and the protection circuit tripped as expected at the low-voltage cutoff threshold before any cell dropped below safe limits.
• Monthly discharge cycle for GO + Play 3: If this speaker sits on a desk or shelf and gets topped off daily, let it run down below 20% at least once a month before recharging. Constant partial-charge cycles without a full discharge cause fuel gauge drift on the 18650 cells, and the speaker will begin reporting false full-charge readings well before actual capacity loss is noticeable.

Audio distorting before the battery indicator reaches empty on the GO + Play 3

This happens because the Class D amplifier inside the GO + Play 3 draws a sharp current spike at high volume, pulling the pack voltage down faster than the fuel gauge tracks. When cell voltage sags under that combined amplifier and radio load, the amplifier clips before the indicator catches up. The battery indicator reads the resting voltage between bursts, not the loaded voltage under a loud transient — so the display looks fine while the audio is already distorting. If you hear clipping with charge remaining, check the actual loaded voltage at the pack connector; a healthy cell should stay above 9.9V under load at 50% indicated charge.

GO + Play 3 won't wake from USB when the pack has been sitting discharged for weeks

Li-ion cells left in a deeply discharged state drop below the minimum acceptance voltage that USB-C PD and standard 5V chargers can handshake against. The speaker's charge circuit will not initiate a charge cycle if the pack has self-discharged below roughly 2.5V per cell (7.5V total). At that point the speaker appears completely dead — no LED, no audio, no response. To recover, apply a controlled low-current pre-charge using a lab supply or a charger with a recovery mode at around 8–9V before returning it to the standard USB charge path.