Sony Ericsson BA750 Xperia Arc Replacement Battery 3.7V 1200mAh

Sony Ericsson Xperia Arc / LT15i — 3.7V Li-ion Replacement Battery (BA750)

This is a 3.7V, 1200mAh Li-ion cell built to the BA750 specification for the Sony Ericsson Xperia Arc. It fits the LT15a, LT15i, and Anzu variants — any device originally shipped with a BA750. The cell slots into the same battery bay and connects to the same fuel gauge IC as the original.

• LT15a, LT15i, and Anzu compatibility: All three share the same 3.7V single-cell architecture, identical connector pinout, and the same fuel gauge IC communication bus. One cell fits all without adaptation.
• Bench tested on actual hardware: We ran this cell on an LT15i under mixed screen-on and modem load. The BMS held stable voltage through full discharge and accepted charge without tripping the protection circuit at any point in the cycle.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to automatic shutdown — then charge uninterrupted to 100% before enabling any fast-charge option. The Xperia Arc's fuel gauge IC needs one full discharge-charge pass against the new cell's actual discharge curve before its coulomb counter reads accurately.

Why the Xperia Arc reports wrong battery percentage after a cell swap

The Xperia Arc uses a fuel gauge IC that tracks charge by counting coulombs against a stored discharge curve. That curve was calibrated to the original BA750 cell — often one that had already degraded. When a fresh cell goes in, the IC still references the old curve, so it misreads state of charge. The fix is one full uninterrupted discharge to shutdown followed by a full charge to 100%. After that cycle the IC updates its reference and percentage readout stabilises.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC reports 20–30% remaining but the cell voltage drops below the BMS cutoff threshold under modem or display load. The IC thinks charge remains, but the cell cannot sustain voltage when current demand spikes. It is not a defective cell — it is an uncalibrated fuel gauge reading a flat discharge curve. Run one full cycle as described above and confirm the cell holds above 3.5V under load before dismissing the shutdown as a hardware fault.