HTC S620 EXCA160 Replacement Battery 3.7V 2200mAh

HTC S620 — 3.7V Li-ion Replacement Battery (EXCA160)

This is a 3.7V, 2200mAh Li-ion replacement battery for the HTC S620 smartphone. It fits the S620 directly, matching the original cell footprint at 55.82 × 35.90 × 10.11mm. OEM part numbers EXCA160 and 35H00080-00M both cross-reference to this cell.

• HTC S620 fitment: The S620 uses a single-cell 3.7V Li-ion pack with a specific connector pinout and BMS communication line. This cell matches that pinout, so the phone's charge controller and fuel gauge IC handshake without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the S620 platform. The BMS accepted the charge curve without tripping cutoff, and the fuel gauge IC tracked state-of-charge through the full discharge sweep.
• Fuel gauge recalibration after install: On first use after fitting this cell, disable any fast-charge accessory and run one complete discharge-to-charge cycle at standard current. This lets the fuel gauge IC map its calibration against the new cell's discharge curve before high-current charging pushes load into an uncalibrated state.

Why the S620 reports wrong battery percentage after a cell swap

The S620's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the new cell's actual voltage-to-capacity relationship. The phone reads voltage from the cell and maps it against the old curve, so the percentage displayed is off — sometimes significantly. One full discharge cycle followed by a full charge resets the coulomb counter and lets the IC relearn the new curve.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under load — modem transmit bursts or screen-on draw pull current the cell cannot sustain at that state-of-charge. The BMS reads the voltage cliff as a low-cell condition and cuts output before the gauge hits zero. It is not a faulty cell — it is the fuel gauge IC reading a miscalibrated curve. Run two full discharge-charge cycles at standard charge current, and the shutdowns typically stop once the IC has recalculated the voltage cliff point for the new cell.