JBL Tuner 2 IAA004NA Replacement Battery 3.7V 2600mAh

JBL Tuner 2 — 3.7V Li-ion Replacement Battery (IAA004NA)

This is a 3.7V 2600mAh Li-ion cell built to the IAA004NA spec, fitting the JBL Tuner 2 portable Bluetooth speaker. It replaces the original pack when the speaker no longer holds a charge or dies mid-session. Dimensions are 71.00 × 20.00 × 20.00mm — confirm against your existing cell before ordering.

• Tuner 2 fit: The Tuner 2 uses a single flat Li-ion cell wired to a small protection circuit. The IAA004NA spec matches the connector pinout and cell voltage that the speaker's charge management IC expects. Swapping an off-spec cell can confuse the charge circuit and prevent the device from switching on.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Tuner 2 board. The protection circuit tripped correctly at low-voltage cutoff, and the charge IC accepted the cell without fault flags on the status LED sequence.
• Fuel gauge reset after install: After fitting a new cell, let the Tuner 2 discharge to the point where it shuts off automatically before recharging to full. Skipping this step causes the fuel gauge IC to read from stale calibration data, so the battery indicator will show empty or full at the wrong state of charge.

Capacity fade from constant top-off charging on the Tuner 2

The Tuner 2 sits on a desk or shelf and most users plug it in whenever it dips below 50%. That shallow-cycle pattern stresses the Li-ion cell at the top of its charge curve, where heat and electrode wear accumulate fastest. Over several months, usable capacity drops noticeably even though the cell has few "full" cycles logged. Letting the pack drop below 20% at least once a month before a full recharge slows that degradation curve.

Audio distorting before the battery indicator shows empty

As the cell ages, internal resistance climbs. When the amplifier draws a current spike at higher volume, the terminal voltage sags below what the amp needs to stay in its linear range — even if the fuel gauge still shows charge remaining. The result is audible clipping or crackle that sounds like a speaker fault but clears when volume drops. If distortion starts while the indicator shows two or more bars, check resting voltage with a multimeter — a healthy cell at partial charge should read above 3.6V at rest.