About this replacement
JBL Charge 5 — 3.7V Li-ion Replacement Battery (GSP-1S3P-CH4A)
This 3.7V, 10000mAh Li-ion cell replaces the original pack in the JBL Charge 5 portable Bluetooth speaker. It also fits the Charge 4 using part number GSP-1S3P-CH4A. Capacity is 10000mAh (37Wh), matching the factory specification.
- Charge 4 and Charge 5 compatibility: Both speakers share the GSP-1S3P-CH4A cell format, the same 3.7V nominal voltage rail, and the same BMS connector pinout. The Charge 5 also accepts the GSP-1S3P-CH4D variant. Swapping between generations works because the pack geometry and protection circuit communication are identical.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the Charge 5 board. The BMS handshake completed without error, fuel gauge reporting tracked correctly across the discharge curve, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
- Fuel gauge reset after fitting: After installing a new cell, the Charge 5 fuel gauge often reads inaccurate percentages because it was calibrated to the old degraded pack. Run the speaker down until it shuts off automatically, then charge it uninterrupted to 100% — this recalibrates the gauge to the new cell's actual capacity.
Capacity fade from constant top-off charging on the Charge 5
Most Charge 5 owners keep the speaker plugged in at a desk and top it off before it drops below 50%. Li-ion cells cycled repeatedly between 80% and 100% never complete a full charge-discharge cycle, which causes the fuel gauge to drift and accelerates capacity loss at the top of the voltage curve. The cell voltage sits near 4.2V for extended periods, which stresses the cathode chemistry. Discharge the pack to below 20% at least once a month before putting it back on charge.
Audio distorting before the battery indicator reaches empty
At high volume, the amplifier inside the Charge 5 draws current in short, sharp spikes. When the cell is partially discharged, internal resistance rises enough that those spikes cause the voltage to sag below what the amp needs — the result is clipping distortion even though the indicator shows charge remaining. This is a cell-level issue, not a speaker fault. A fresh cell with lower internal resistance holds voltage more steadily under the amplifier's peak draw. If distortion starts appearing above 70% volume, check the resting voltage of the old pack — a healthy cell at 50% charge should read above 3.7V at rest.