Samsung Galaxy S II Replacement Battery 3.7V 1300mAh

USCellular Galaxy S II (SCH-R760) — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1300mAh Li-ion battery for the Samsung Galaxy S II on the USCellular network, specifically the SCH-R760 variant. It slots into the standard battery bay and connects via the same three-contact terminal used on the original cell. Swap it when the original no longer holds a charge or fails to power the device.

• SCH-R760 carrier variant: USCellular's Galaxy S II shares the same battery bay dimensions and contact pinout as the international i9100, but the SCH-R760 firmware may report different charge states depending on the cell's internal resistance signature. This 1300mAh cell matches the original capacity spec so the fuel gauge IC has a realistic baseline to work from.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Galaxy S II unit. The BMS accepted charge without triggering overvoltage cutoff, and the protection circuit responded correctly to a simulated short at the terminals.
• Fuel gauge recalibration after install: On first use, disable any fast-charge adapter and run one full discharge-to-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before the phone starts making load decisions based on percentage readings.

Why the SCH-R760 reports wrong battery percentage after a cell swap

The Galaxy S II uses a coulomb counter in the fuel gauge IC to track charge state. That counter was calibrated against the discharge curve of the original cell. A new cell with even a slightly different internal resistance profile will cause the IC to read percentages that don't match real capacity. The fix is one full uninterrupted discharge down to automatic shutdown, followed by a full charge to 100% — this resets the coulomb counter's reference points. After that cycle, percentage reporting stabilises.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under modem or display load — a voltage cliff the fuel gauge IC didn't predict because it was still using the old cell's curve. The phone's software cuts power before the percentage reaches zero because the actual cell voltage has already fallen below 3.2V under load. Run the full recalibration cycle described above. If shutdowns persist after two full cycles, check that the battery contacts on the phone are clean and making firm contact — poor contact increases resistance and steepens the voltage sag under load.