JBL Authentics 300 Replacement Battery 3.7V 5200mAh C1146A9

JBL Authentics 300 — 3.7V Li-ion Replacement Battery (C1146A9)

This 3.7V, 5200mAh Li-ion cell replaces the original C1146A9 battery in the JBL Authentics 300 smart home speaker. It restores wireless portability when the original pack degrades, loses capacity, or stops holding a charge. Dimensions are 72.00 × 38.50 × 20.90mm — confirm these against your existing cell before ordering.

• Authentics 300 cell compatibility: The Authentics 300 runs a single-cell 3.7V Li-ion configuration with a proprietary BMS handshake. This replacement matches that voltage rail and connector pinout, so the onboard protection circuit communicates with the cell correctly and accepts a charge without throwing a fault.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Authentics 300 platform. The BMS registered the cell correctly, charge termination triggered at the expected cutoff voltage, and the protection circuit tripped cleanly under simulated fault conditions.
• Fuel gauge recalibration after swap: After fitting a new cell, the Authentics 300 fuel gauge can misread state of charge because it was calibrated to the old, degraded pack. Run the speaker down until it shuts off on low battery, then charge to 100% in a single uninterrupted session — this resets the gauge baseline so the indicator reads accurately.

Audio distorting before the battery indicator reaches empty

As the cell discharges toward its lower cutoff, internal resistance rises and the voltage sags under amplifier load. The Authentics 300's Class D amplifier draws sharp current spikes at higher volumes, and those spikes pull cell voltage below the clean-audio threshold before the fuel gauge reads empty. The result is clipping and distortion — not a speaker driver fault. Reducing volume by 20–30% at low charge levels keeps the cell above the sag threshold and clears the distortion without any hardware change.

Speaker won't wake from USB-C when the pack has been fully drained

If the Authentics 300 sits unused until the cell fully self-discharges, the cell voltage can fall below the USB-C PD minimum acceptance threshold — typically around 2.5V. At that point the charger and the speaker's protection circuit cannot negotiate a handshake, and the speaker appears completely dead on USB-C. Connect the original cable and leave it for 15–20 minutes without pressing any buttons — the BMS uses a trickle pre-charge routine to bring the cell back up to a voltage where normal PD negotiation can resume, after which charging proceeds normally.