About this replacement
Harman/Kardon Onyx Studio 4 — 3.7V Li-ion Replacement Battery (ICR22650)
This is a 3.7V, 3000mAh Li-ion cell for the Harman/Kardon Onyx Studio 4 portable Bluetooth speaker. It replaces the original ICR22650 format cell when the pack no longer holds a useful charge or fails to power the speaker at all. Fits both the Onyx Studio 4 and Onyx 4 variants.
- Onyx Studio 4 and Onyx 4 compatibility: Both models use the same ICR22650 cylindrical cell, share the same 3.7V nominal voltage rail, and draw from the same connector layout on the charging board — one cell fits both without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Onyx Studio 4 platform. The BMS accepted the cell without error, balanced correctly at 4.2V full charge, and held the protection cutoff at the expected low-voltage threshold under amplifier load.
- Monthly discharge cycle for the Onyx 4: This speaker gets topped off constantly on desks and shelves. Let the battery drop below 20% at least once a month before recharging — skipping full discharge cycles causes fuel gauge drift and speeds up capacity fade on the ICR22650 cell.
Audio distorting before the battery indicator reaches empty
As the ICR22650 cell ages, its internal resistance rises. Under high amplifier load, the cell voltage sags below what the amp needs even though the fuel gauge still reads 20–30%. The amplifier clips because it cannot draw enough clean current, and distortion appears well before the low-battery warning fires. Replacing the cell restores the voltage floor and eliminates the sag that causes early clipping.
Speaker won't wake from USB-C after sitting unused for weeks
A deeply discharged ICR22650 cell can drop below the minimum acceptance voltage for USB-C PD negotiation — typically under 2.5V. At that level, the charger handshake fails and the speaker appears completely dead rather than charging. To recover, connect to a 5V USB-A charger instead of USB-C, which bypasses PD negotiation and trickle-charges the cell back above the 2.7V reinitialisation threshold before switching to normal charge rate.