HTC S620 EXCA160 Replacement Battery 3.7V 1050mAh Li-ion

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

This is a 3.7V, 1050mAh Li-ion cell replacing the original battery in the HTC S620, S621, Excalibur, and Excalibur 100 smartphones. It slots into the same battery bay and connects via the original contacts. Capacity figure is 1050mAh — use this number, not estimates from third-party sources.

• S620 / Excalibur platform fit: The S620, S621, Excalibur, and Excalibur 100 all run the same battery bay geometry, contact pin layout, and 3.7V voltage rail. One cell covers the full range because HTC kept the battery spec consistent across this hardware generation.
• Bench tested on actual hardware: We ran this cell on the S620 platform and confirmed the BMS handshake completes correctly — the phone exits boot without triggering a low-voltage cutoff and the charge IC accepts a full charge cycle without erroring out.
• Fuel gauge recalibration on first cycle: After fitting this cell, disable any fast-charge accessory and run one complete discharge-to-charge cycle. The S620 fuel gauge IC calibrates against the cell's discharge curve on that first pass — skip it and the percentage readout will track the old cell's curve, not this one.

Why the S620 reports wrong battery percentage after a cell swap

The S620 uses a fuel gauge IC that builds its state-of-charge model from charge and discharge history. When a new cell goes in, the IC still holds the old cell's learned curve. Until it runs at least one full discharge and charge cycle on the new cell, the percentage on screen reflects outdated data. This is not a fault with the replacement cell — it is the IC doing what it was built to do. Run one uninterrupted discharge down to auto-shutdown, then charge fully, and the gauge resets its reference points against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC has not yet recalibrated and the phone's software cuts power based on a voltage threshold that no longer matches the new cell's discharge curve. Under load — screen on, data active, or a call in progress — the cell voltage drops faster than the uncalibrated gauge predicts, and the device shuts down before the displayed percentage reaches zero. The fix is the same recalibration cycle: one full discharge to auto-shutdown followed by a complete charge. After that cycle, the gauge tracks actual cell voltage under load and the early-shutdown behaviour stops. Confirm the cell is holding above 3.6V at rest after a full charge before concluding the issue persists.