JBL Micro 2 Replacement Battery 3.7V 600mAh FT403048P

JBL Micro 2 / Clip Series — 3.7V Li-Polymer Replacement Battery (FT403048P)

This 3.7V, 600mAh Li-Polymer cell replaces the original FT403048P battery in the JBL Micro 2, Micro II, Clip, and Clip+. It restores power to the compact speaker when the original cell no longer holds a charge or fails to accept a charge cycle. Dimensions are 50.40 × 30.00 × 4.80mm — measure your existing cell before ordering if you are unsure.

• Micro 2, Micro II, Clip, and Clip+ compatibility: These models share the same FT403048P cell footprint and 3.7V supply rail. The connector pinout and BMS handshake voltage are identical across the group, so one cell covers all four units.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a JBL Micro 2 unit. The onboard BMS accepted the cell without fault flags, and the fuel gauge read accurately at both ends of the cycle.
• Monthly full-discharge cycle for Micro 2 users: If the speaker sits on a desk and gets topped off before it drops below 50%, run it down past 20% at least once a month before recharging. Constant shallow cycling causes fuel gauge drift on this cell and accelerates capacity fade faster than deep cycling does.

Why the Micro 2 reports full charge but audio cuts out after extended play

The Micro 2 fuel gauge reads state-of-charge from a coulomb counter, not a direct voltage measurement. After months of shallow top-off charging, the counter drifts and the reported percentage no longer matches actual cell capacity. The speaker shuts down to protect the cell even though the display still shows partial charge. A full discharge to near-empty followed by an uninterrupted charge resets the counter and brings the gauge back into alignment.

Audio distorting before the battery indicator reaches empty

As the Li-Polymer cell discharges, internal resistance rises and voltage sags under the combined draw of the amplifier and Bluetooth radio. At high volume, that sag pushes the supply voltage below the amplifier's clean operating threshold before the battery indicator reaches zero. The result is audible clipping and distortion on bass-heavy tracks. If you hear distortion while the indicator still shows charge remaining, drop the volume and charge the cell — voltage at the amp input is already too low for undistorted output.