About this replacement
Harman/Kardon Onyx Studio 8 — 3.7V Li-ion Replacement Battery (ICA077NA)
This is a 3.7V 3350mAh (12.4Wh) Li-ion replacement battery for the Harman/Kardon Onyx Studio 8 portable Bluetooth speaker. It fits directly in place of the original ICA077NA cell. Order this when the original pack no longer holds enough charge to support a full listening session.
- Onyx Studio 8 fitment: The Onyx Studio 8 uses a single-cell Li-ion pack at 3.7V nominal. The connector pinout and BMS communication protocol on this replacement match the original so the speaker's charge indicator reports state-of-charge correctly after installation.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Onyx Studio 8 platform. The BMS accepted the pack without fault codes, and the fuel gauge calibrated correctly within the first full charge cycle.
- Monthly discharge cycle for Onyx Studio 8 users: Speakers kept plugged in or topped off constantly never fully discharge the cell, which causes fuel gauge drift over time. Run the Onyx Studio 8 down below 20% at least once a month before recharging to keep the gauge accurate and slow capacity fade on the Li-ion cell.
Audio distorting before the battery indicator reaches empty on the Onyx Studio 8
As the cell discharges toward its lower cutoff, the amplifier inside the Onyx Studio 8 draws more current than the voltage rail can cleanly supply. This causes the output stage to clip, producing audible distortion even while the battery indicator still shows one or two bars. It is not a speaker driver fault — it is voltage sag under amplifier load. A fresh cell with lower internal resistance holds the rail closer to 3.6V longer, pushing the distortion threshold much closer to actual empty.
Onyx Studio 8 not responding to USB-C charge after sitting unused for months
A deeply discharged Li-ion cell can fall below the minimum voltage a USB-C Power Delivery charger will recognise — typically around 2.5V — and the handshake never completes. The speaker appears completely dead even with a known-good cable. Try a charger that supports 5V 0.5A trickle output, which bypasses PD negotiation and can bring the cell back above the 2.5V threshold. Once the indicator LED flickers, switch to your normal charger and allow a full charge before testing playback.