JBL E25BT Replacement Battery 3.7V 140mAh GSP051230

JBL E25BT / T110BT — 3.7V Li-Polymer Replacement Battery (GSP051230)

This is a 3.7V, 140mAh Li-Polymer cell that fits the JBL E25BT and T110BT wireless in-ear earbuds. It replaces the original GSP051230 cell inside a single earbud unit. Swap it in when the original cell has degraded and the earbud no longer holds a charge between uses.

• E25BT and T110BT compatibility: Both models share the same internal cell footprint, connector pinout, and 3.7V nominal voltage rail. The GSP051230 cell fits either unit without modification to the BMS communication line.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on E25BT hardware. The BMS accepted the new cell without fault codes, and the protection circuit engaged correctly at low-voltage cutoff.
• First-cycle charge tip for E25BT: After fitting, run a complete charge cycle before using the earbud. The onboard fuel gauge in the E25BT resets its calibration point on the first full charge — skipping this step causes the battery indicator to read inaccurately from day one.

Why the E25BT cuts out mid-audio on a new battery

The E25BT combines Bluetooth radio draw and audio driver current in a very small housing. On a fresh cell sitting at storage voltage — typically around 3.6V — the combined draw during peak audio output can trip the BMS undervoltage protection even though the cell is not depleted. This is not a faulty cell. Run two or three full charge-discharge cycles and the BMS will stop triggering at storage voltage levels.

Earbud shows full charge on the case but dies quickly after removal

This happens when a replacement cell arrives at shipping voltage and the charging case logs the charge state before the first full cycle completes. The case reads the surface charge — around 3.8–3.9V — and reports full. The actual usable capacity is lower until the cell has been cycled at least once from full charge to cutoff. Charge the earbud to 100% inside the case, use it until it powers off, then charge again. After that first complete cycle, the reported charge level will track actual capacity accurately.