BST279BSA Samsung SCH-I730 Compatible Battery 3.7V 1150mAh

Samsung SCH-I730 / SGH-I730 — 3.7V Li-Polymer Replacement Battery (BST279BSA)

This is a 3.7V, 1150mAh Li-Polymer replacement battery for the Samsung SCH-I730, SGH-I730, and SPH-M4300. It carries OEM part number BST279BSA and slots directly into the original battery bay. Capacity is 1150mAh (4.26Wh), matching the stock cell specification.

• SCH-I730, SGH-I730, SPH-M4300 compatibility: All three models share the same 3.7V Li-Polymer cell format, connector pinout, and BMS handshake protocol — one battery fits all three without modification or adapter.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SCH-I730 platform. The BMS accepted the handshake on first connection, charge current ramped normally through CC/CV stages, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first install: On first use after fitting this cell, disable any fast-charge mode and run one full discharge-to-charge cycle. This allows the fuel gauge IC to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state — preventing erratic percentage readings from the start.

Sudden shutdown at 20–30% on the SCH-I730 after a cell swap

A new Li-Polymer cell has a slightly different voltage-versus-capacity curve than the aged cell the fuel gauge IC was last calibrated to. When the phone draws high current — during a call, data sync, or screen-on activity — the cell voltage dips below the modem's minimum rail threshold before the percentage counter reaches zero. The phone interprets this as a hard power failure and shuts down, even though the displayed charge still shows 20–30%. One full discharge cycle down to automatic cutoff, followed by an uninterrupted charge to 100%, resets the coulomb counter against the actual cell curve and resolves the premature shutdown.

Phone warm near the battery during the first charge cycle after replacement

A new Li-Polymer cell typically has higher internal impedance on its first few charge cycles than a broken-in cell. The charge IC pushes the same current it used on the lower-impedance old cell, and that impedance mismatch converts more energy to heat than usual. This is normal during the first one to three cycles and the temperature should drop as the cell conditions. If the back of the phone stays hot past the third full charge cycle, check that the cell is seated flat against the battery contacts and that no connector pin is bent — a misaligned pin forces the charge IC to compensate with higher voltage, sustaining the heat.