BA S470 T-Mobile myTouch HD Replacement Battery 3.7V 1050mAh

T-Mobile myTouch HD / PD98120 — 3.7V Li-ion Replacement Battery (BA S470)

This is a 3.7V, 1050mAh Li-ion cell that fits the T-Mobile myTouch HD and PD98120 smartphones. It replaces OEM part numbers BA S470, BD26100, 35H00141-00M, 35H00141-02M, and 35H00141-03M. The battery restores power to the processor, display, and wireless radios when the original cell has degraded.

• myTouch HD and PD98120 compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The cell measures 54 × 43 × 5mm — swap clearance is tight, so seat the connector fully before closing the rear cover.
• Bench tested on actual hardware: We cycled this cell on the myTouch HD platform and confirmed the BMS negotiates charge termination correctly at 4.2V. Charge current stepped down as expected at the top-of-charge threshold with no false cutoff.
• Fuel gauge recalibration on first cycle: On first use after installation, run one full discharge down to auto-shutdown, then charge to 100% without interruption. This gives the coulomb counter a full reference sweep against the new cell's discharge curve before the OS starts reporting capacity.

Why the myTouch HD reports wrong battery percentage after a cell swap

The myTouch HD uses a fuel gauge IC that tracks charge state by counting coulombs against a learned discharge curve from the previous cell. Drop in a new cell and that stored curve no longer matches the physical chemistry. The OS reads the old model and outputs a percentage that drifts from reality — sometimes optimistic, sometimes crashing early. One complete discharge-to-shutdown followed by a full uninterrupted charge resets the learned curve to the new cell. After that cycle, percentage reporting stabilises.

Sudden shutdown at 20–25% on the replacement cell

This happens when the modem or display pulls a current spike the cell cannot sustain at a low state of charge — voltage drops below the BMS cutoff threshold even though the gauge still shows charge remaining. The fuel gauge IC hasn't yet mapped the new cell's voltage cliff, so it doesn't warn the OS in time. It is not a defective cell — it is a calibration gap. Complete the recalibration cycle above; the voltage cliff gets mapped, and the OS receives an earlier low-battery signal before the next shutdown event. If the problem persists past two full cycles, check that the battery connector is fully seated and that contact resistance is not adding to the voltage sag.