JBL T600 BT Replacement Battery 3.7V 600mAh Li-Polymer

JBL T600 BT / Tune 600BTNC — 3.7V Li-Polymer Replacement Battery (GSP753030 01)

This is a 3.7V, 600mAh lithium-polymer battery for the JBL T600 BT and Tune 600BTNC wireless headphones. It replaces the original GSP753030 01 cell when the existing pack no longer holds a charge. Dimensions are 32.50 × 28.50 × 7.00mm — confirm clearance inside the ear cup housing before fitting.

• T600 BT and Tune 600BTNC compatibility: Both headphones share the same ear cup chassis, connector pinout, and fuel gauge IC — this is why a single cell covers both models. The BMS handshake is identical across the T600 BT and Tune 600BTNC production runs.
• Bench tested on actual hardware: We ran the GSP753030 01 cell through charge and discharge cycles on the T600 BT. The BMS accepted charge at the standard 4.2V cutoff, and the fuel gauge reported accurately across the full state-of-charge range without false-full flags.
• Monthly discharge cycle for T600 BT users: If these headphones sit on a desk and get topped off constantly, discharge them below 20% at least once a month before recharging. Constant shallow cycling causes fuel gauge drift on this cell — the indicator shows full but playtime shrinks noticeably over weeks.

Bluetooth dropping at high volume on the T600 BT after battery replacement

At high playback volume, the amplifier and Bluetooth radio draw current simultaneously — this is the peak load condition for the 600mAh cell. If the replacement cell has any internal resistance above spec, voltage sags enough during that combined draw to trip the BMS or drop the radio link. The headphones appear to reconnect within seconds, which is the BMS recovering after the spike. Check the solder pads on the connector after fitting — a cold joint adds resistance and makes this worse.

Audio distorting before the battery indicator reaches empty

This happens when cell voltage drops below the amplifier's minimum operating threshold before the fuel gauge reaches zero. The amplifier clips under voltage sag and the output sounds like buzzing or crackling — it is not a driver or firmware fault. The fuel gauge IC in the T600 BT is calibrated to the original cell's discharge curve, so a degraded or mismatched cell will read higher than the actual state of charge. Running a full discharge to the automatic shutoff point once resets the gauge against the new cell's curve.