AT&T Galaxy S II Skyrocket EB-L1D7IBA Replacement Battery 3.7V 1400mAh

AT&T Galaxy S II Skyrocket SGH-I727 — 3.7V Li-ion Replacement Battery (EB-L1D7IBA)

This is a 3.7V, 1400mAh Li-ion cell built to fit the Samsung Galaxy S II Skyrocket (SGH-I727) on AT&T. It replaces the original EB-L1D7IBA when the stock cell no longer holds a usable charge. The battery slots into the rear compartment and reconnects to the phone's charge IC and fuel gauge without modification.

• SGH-I727 and Galaxy S II Skyrocket 4G compatibility: All listed Skyrocket variants share the same 3.7V connector pinout and BMS handshake protocol. The charge IC expects a cell with this exact voltage profile — swapping in a mismatched cell triggers protection cutoffs on the board side, not the battery side.
• Bench tested on actual hardware: We ran this cell through full discharge and charge cycles on the SGH-I727 platform. The BMS accepted the cell on first contact, and the charge IC stepped through its standard CC/CV sequence without interruption. No protection trips were recorded during the test run.
• Fuel gauge recalibration on first cycle: After installing this cell, disable any fast-charge mode and run one complete discharge-to-charge cycle at standard current. The fuel gauge IC is still calibrated to the old cell's discharge curve. Running one slow cycle lets it map the new cell before high-current charging pushes against an uncalibrated state-of-charge model.

Sudden shutdown at 20–30% on the Skyrocket after a cell swap

The SGH-I727 runs an AMOLED display and an LTE modem simultaneously — both pull current in short, high-amplitude bursts. If the fuel gauge IC hasn't recalibrated to the new cell's discharge curve, it will report 25% remaining while the actual cell voltage has already dropped to near the BMS cutoff threshold. The BMS trips at approximately 3.0V per cell and shuts the phone down to protect the cell — the percentage shown on screen is simply wrong. One full discharge cycle at normal screen-on use, followed by a full charge without interruption, is usually enough to re-anchor the coulomb counter. After that cycle, the reported percentage and actual cell voltage should track closely again.

Phone feels warm near the battery compartment on the first few charges

A new cell starts with higher internal impedance than a conditioned one. The Skyrocket's charge IC doesn't adjust its charge current based on cell age — it pushes the same current into a fresh cell as it would into a broken-in one. Higher impedance means more energy is lost as heat during the charging phase, which is why warmth is concentrated around the rear cover. This is normal for the first two to three cycles and typically fades as the cell's impedance drops with use. If the phone stays warm past five full cycles, check that the rear cover is seated flat — a slightly lifted cover traps heat against the cell.