JBL Charge 3 Replacement Battery GSP1029102A 3.7V 6000mAh

JBL Charge 3 / Charge 3 Stealth Edition — 3.7V Li-Polymer Replacement Battery (GSP1029102A)

This 3.7V, 6000mAh Li-Polymer battery replaces the original GSP1029102A cell in the JBL Charge 3 and Charge 3 Stealth Edition portable Bluetooth speakers. It fits both variants — the standard and all-black Stealth edition share the same battery bay and connector. Swap it when the original no longer holds a charge or shuts down under audio load.

• Charge 3 and Stealth Edition compatibility: Both models use the same 3.7V single-cell architecture, identical connector pinout, and the same BMS communication protocol. The battery slots in without modification to either housing variant.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Charge 3 unit. The onboard BMS accepted the cell without fault codes, cell balance held across full cycles, and the protection circuit triggered correctly at low-voltage cutoff.
• Charge cycle discipline for daily-use speakers: Let the Charge 3 drain below 20% at least once a month before plugging in. Constant top-off charging from 60–80% without full discharge cycles causes fuel gauge drift — the speaker reports full battery but actual capacity is significantly lower.

Voltage sag under amplifier load at high volume on the Charge 3

The Charge 3 amplifier pulls a sharp current spike when you push volume above 80%. On a degraded or deeply discharged cell, this spike drops the terminal voltage fast enough to trip the BMS undervoltage protection. The speaker cuts out, recovers, then cuts again — a cycle that looks like a Bluetooth issue but is actually a battery problem. A fresh 6000mAh cell with low internal resistance handles those transient spikes without the voltage rail collapsing below the BMS threshold.

Speaker shows full charge indicator but shuts down after short playback

This is fuel gauge drift, not a charging fault. The Charge 3 fuel gauge IC calibrates its state-of-charge estimate against previous cycle data. If the battery has been shallow-cycled for months — always charged before it drops below 50% — the gauge loses accuracy and reports 100% on a cell that may only have 30–40% usable capacity remaining. Replacing the cell resets the baseline, but you need to run two or three full discharge-to-charge cycles after fitting to let the gauge re-calibrate. Discharge to below 3.5V per cell before each recharge during those first cycles.