Jawbone Big Jambox 11.1V 3400mAh Replacement Battery J200

Jawbone Big Jambox — 11.1V Li-ion Replacement Battery (J200/ICR18650F1L)

This is an 11.1V, 3400mAh Li-ion battery pack for the Jawbone Big Jambox portable Bluetooth speaker. It fits J2011-03-US and J2011-02-US units. When the original pack degrades, this replacement restores wireless playback without keeping the speaker tethered to a power outlet.

• Big Jambox compatibility (J2011-03-US, J2011-02-US): Both model variants run the same 11.1V three-cell Li-ion configuration with the same connector and BMS handshake. The pack voltage rail feeds both the amplifier board and the Bluetooth radio, so the BMS must regulate output across that combined load.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the Big Jambox board. The BMS held stable output across combined amplifier and radio draw, and charge termination triggered correctly at cell capacity without overrun.
• Monthly discharge cycle for Big Jambox users: If the speaker lives on a desk and gets topped off constantly, let it run below 20% at least once a month before recharging. Constant shallow cycling causes fuel gauge drift on this pack, and the charge indicator will stop reflecting actual remaining capacity.

Audio distortion before the battery indicator reaches empty on the Big Jambox

As cell voltage drops toward the end of a discharge cycle, the amplifier board receives less voltage than it needs to drive the speaker at higher volumes. The amplifier clips the signal before the BMS hits its low-voltage cutoff, so the speaker distorts while the battery indicator still shows charge remaining. This happens earlier on an aged pack because internal cell resistance rises, increasing voltage sag under load. A fresh pack at 11.1V nominal holds the voltage rail steady longer, pushing that clipping threshold back.

Bluetooth cutting out at high volume on the Big Jambox

The Big Jambox pulls from a shared rail — the amplifier and the Bluetooth radio both draw from the same pack output. At loud playback, the amplifier current spike momentarily sags the rail voltage, and the radio loses enough power to drop its connection. A degraded cell with high internal resistance makes that sag worse. If Bluetooth drops consistently at high volume but recovers at lower levels, the pack's ability to maintain voltage under combined load has declined — replace the pack and check that the connector is fully seated.