About this replacement
Samsung SCH-W579 — 3.7V Li-ion Replacement Battery
This 3.7V Li-ion battery replaces the original cell in the Samsung SCH-W579 smartphone. It carries a 1000mAh (3.7Wh) capacity, matching the stock specification for this handset. Fits directly into the SCH-W579 battery compartment.
- SCH-W579 fit: The SCH-W579 uses a compact 3.7V single-cell Li-ion pack with a low-current BMS matched to this phone's charge IC. Swapping to a cell outside that voltage window causes the phone to reject the pack at the connector handshake level.
- Bench tested on actual hardware: We cycled this cell through full charge and load discharge on the bench. The BMS held cutoff voltage cleanly and the charge IC accepted the pack without fault codes on the first cycle.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle before resuming normal use. This gives the fuel gauge IC time to map the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated register.
Why the SCH-W579 reports wrong battery percentage after a cell swap
The SCH-W579 uses a fuel gauge IC that stores a learned discharge curve from the original cell. When a new cell goes in, the IC is still referencing old impedance and capacity data. The percentage shown on screen reflects the old curve, not the new cell's actual state of charge. One full discharge down to auto-shutoff followed by a full charge resets the coulomb counter and re-anchors the gauge to the new cell.
Sudden shutdown at 20–30% remaining on the replacement cell
This happens when the cell voltage drops sharply under modem or display load — a voltage cliff that the fuel gauge didn't predict. The phone's protection circuit reads the sag as a critical low-voltage event and cuts power before the percentage hits zero. The root cause is an uncalibrated fuel gauge mapping a steep-discharge cell as if it were the original. Run two full discharge-charge cycles and the gauge IC will recalibrate its cutoff threshold closer to the real 3.0V floor of the cell.