JBL Authentics 300 Replacement Battery 3.7V 6700mAh C1146A9

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

This 3.7V, 6700mAh Li-ion cell replaces the original C1146A9 battery in the JBL Authentics 300 portable Bluetooth speaker. It restores wireless audio playback after the factory cell has degraded or failed. Capacity is rated at 24.79Wh — matched to the stock specification.

• Authentics 300 fitment: The Authentics 300 uses a single-cell Li-ion pack at 3.7V nominal. The BMS inside the speaker manages charge termination and low-voltage cutoff directly, so the replacement cell only needs to match the voltage, capacity, and connector — which this one does.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Authentics 300 platform. The onboard BMS accepted the cell without fault flags, balanced charge termination fired correctly at 4.2V, and low-voltage cutoff triggered at the expected threshold without hard shutoff errors.
• Fuel gauge reset after swap: After fitting a new cell, run the Authentics 300 down to the low-battery indicator before the first recharge — this lets the speaker's fuel gauge recalibrate to the new cell's actual capacity and prevents false "full charge" readings from the first cycle onward.

Capacity fade from constant top-off charging on the Authentics 300

Most Authentics 300 owners keep the speaker plugged in on a desk or shelf, topping it off before it drops below 50%. Li-ion cells held continuously near full charge experience elevated stress at the top of the voltage curve, which accelerates capacity loss over time. The symptom is a battery that still reads "full" but delivers noticeably shorter playback before the low-battery warning. Discharging the cell to below 20% at least once a month before recharging helps prevent fuel gauge drift and slows this degradation cycle.

Audio distorting before the battery indicator reaches empty

As the cell voltage sags toward the lower end of its discharge curve, the amplifier inside the Authentics 300 starts to clip before the battery indicator signals low. This produces audible distortion — crackling or thinning bass — even though the speaker shows charge remaining. The cause is voltage sag under combined amplifier and Bluetooth radio draw, not a speaker fault. Charging the cell back above 3.7V nominal typically clears the distortion immediately.