Soundmaster TR150WS Replacement Battery 3.7V 1050mAh

Soundmaster TR150WS — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1050mAh Li-ion replacement cell for the Soundmaster TR150WS mobile device. It slots in when the original cell has degraded past the point of holding a usable charge. Voltage and physical dimensions — 53.00 x 33.90 x 5.60mm — match the original specification.

• TR150WS platform fit: The TR150WS cell uses a fixed form factor tied to the original PCB connector layout and BMS handshake voltage thresholds. Swapping in a mismatched cell — even at the same nominal voltage — can cause the charge IC to reject the cell or report inaccurate capacity to the OS.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, confirming the BMS accepted charge current without fault flags and that the protection circuit tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration after installation: On first use, disable fast charging and run one full discharge-to-charge cycle from 100% to near-empty and back. This lets the fuel gauge IC map the new cell's discharge curve before the OS begins interpolating percentage from an uncalibrated coulomb counter.

Why the TR150WS reports wrong battery percentage after a cell swap

The fuel gauge IC stores a learned discharge curve from the old cell. When a new cell goes in, that curve no longer matches the actual cell chemistry, so the percentage reading drifts — sometimes by 10–20%. The fix is a full calibration cycle: charge to 100%, discharge fully under normal use, then charge back to 100% without interruption. After one complete cycle the coulomb counter resets its reference points against the new cell and the percentage display stabilises.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC is still running against the old cell's voltage curve and the device hits the hardware low-voltage cutoff before the displayed percentage reaches zero. The modem or screen draws a current spike the degraded calibration doesn't account for, and the cell voltage drops below the BMS cutoff threshold instantly. Run the calibration cycle described above — one full discharge and recharge with fast charging disabled. After that cycle, shutdowns in this percentage range should stop.