About this replacement
Harman/Kardon Neo / HKNEOBRNBSG — 3.7V Li-Polymer Replacement Battery (02-553-3494)
This is a 3.7V, 1000mAh Li-Polymer battery for the Harman/Kardon Neo Bluetooth speaker. It fits the Neo and HKNEOBRNBSG variants. Swap it in when the original cell no longer holds a charge or the speaker shuts off unexpectedly during playback.
- Neo and HKNEOBRNBSG compatibility: Both models run the same 3.7V single-cell Li-Polymer architecture with identical connector pinout and BMS handshake protocol — one battery covers both SKUs without any modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Neo platform. The onboard BMS accepted the pack without faulting, balanced charge termination triggered correctly at 4.2V, and protection cutoff activated cleanly at the low-voltage threshold.
- Fuel gauge reset after install: After fitting the new cell, run the speaker down until it auto-shuts off, then charge uninterrupted to 100%. The Neo's fuel gauge IC needs one full cycle to recalibrate — skipping this causes the charge indicator to read inaccurately from day one.
Audio distorting before the battery indicator reaches empty
As a Li-Polymer cell ages, its internal resistance climbs. At moderate-to-high volume, the amplifier draws a short burst of current that the weakened cell can't deliver cleanly, causing the terminal voltage to sag below the amp's operating floor. The audio stage clips under that sag — you hear distortion even though the indicator still shows 20–30% charge remaining. Replacing the cell eliminates the sag; if distortion persists after a fresh battery, check that the speaker firmware is current, as some Neo units shipped with aggressive power-save thresholds that were patched later.
Speaker won't wake from USB after sitting unused for weeks
A deeply discharged Li-Polymer cell can drop below the USB-C PD minimum acceptance voltage — typically around 2.5V — at which point the charger controller on the Neo refuses to initiate a charge session and the speaker appears completely dead. This is a protection circuit response, not a fault in the port or the cable. Connect the speaker to a 5V USB-A source rather than a USB-C PD charger; the lower-power input often coaxes the BMS out of deep-discharge lockout after 10–15 minutes. If the cell has been below 2.5V for an extended period and still won't respond, the cell itself is unrecoverable and requires replacement.