USCellular Galaxy S3 Replacement Battery 3.8V 2100mAh Li-ion

USCellular Galaxy S3 / SCH-R530 — 3.8V Li-ion 2100mAh Replacement Battery

This is a 3.8V Li-ion cell rated at 2100mAh (7.98Wh) for the Samsung Galaxy S3 and Galaxy SIII, including the SCH-R530 and Galaxy SIII LTE variants sold through USCellular. It slots into the removable battery compartment and connects via the standard three-contact pogo strip on the S3 chassis.

• SCH-R530 and SIII LTE compatibility: Both the standard SIII and the LTE variant share the same 3.8V voltage rail, identical physical footprint, and the same three-pin BMS handshake with the Exynos and Snapdragon charge controllers used across the S3 line.
• Bench tested on actual hardware: We cycled this cell through the S3 charge IC and confirmed BMS communication was accepted on first insertion — charge current ramped to CC phase without a BMS rejection error or trickle-lock state.
• Fuel gauge recalibration on first use: On first installation, run one full discharge to automatic shutdown, then charge uninterrupted to 100% before resuming normal use. This gives the coulomb counter a full reference cycle against the new cell's discharge curve before the OS starts reporting state-of-charge.

Why the Galaxy S3 reports wrong battery percentage after a cell swap

The S3 uses a coulomb counter that was calibrated to the original cell's internal resistance and discharge curve over hundreds of cycles. When you drop in a fresh cell with lower impedance, the counter is still using the old curve as its reference. This causes the OS to misread state-of-charge — commonly showing 100% that drops to 80% in minutes, or stalling at a fixed percentage for extended periods. One complete uninterrupted discharge-to-shutdown followed by a full charge resets the calibration baseline.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff symptom, not a capacity problem. When the modem fires during a call or the screen backlight peaks, current draw spikes and the cell voltage momentarily drops below the BMS cutoff threshold — even if the fuel gauge still shows charge remaining. On a freshly installed cell before calibration, the BMS cutoff is set conservatively at around 3.4V under load. Run the full recalibration cycle first; if shutdowns continue after that, check that the battery contacts on the chassis are clean and making full contact, since partial contact increases resistance and deepens the voltage sag.