About this replacement
Sony Ericsson Xperia Arc / LT15i — 3.7V Li-ion Replacement Battery (BA750)
This is a 3.7V, 2500mAh Li-ion cell replacing the OEM BA750 in the Sony Ericsson Xperia Arc, LT15a, and LT15i smartphones. It fits the original battery bay and connects via the same three-contact puck connector on the motherboard. Rated at 9.25Wh, it restores power to a handset that has lost capacity through charge-cycle degradation or cell failure.
- LT15a and LT15i compatibility: Both hardware revisions share the same battery bay dimensions and the same three-pin BMS interface on the board. The BA750 footprint did not change between the two regional variants, so one cell covers both.
- Bench tested on actual hardware: We ran this cell through a full discharge-charge cycle on an LT15i. The charge IC accepted the cell without error, BMS protection tripped correctly at low-voltage cutoff, and the fuel gauge IC tracked state-of-charge without flagging a fault.
- Fuel gauge recalibration on first use: After installation, run one complete discharge to automatic shutdown followed by a full uninterrupted charge before normal use. The Xperia Arc's fuel gauge IC maps its coulomb counter against the new cell's discharge curve during this first cycle — skipping it causes the percentage readout to drift until a full cycle occurs naturally.
Sudden shutdown at 20–30% on the Xperia Arc after a cell swap
This is a voltage cliff issue, not a capacity issue. When the modem fires a transmission burst or the screen jumps to full brightness, instantaneous current draw spikes. A new cell that hasn't completed a calibration cycle may hold a resting voltage that looks healthy to the fuel gauge but drops below the BMS cutoff threshold — around 3.0V per cell — under that load spike. The phone interprets this as a critical low-voltage event and shuts down immediately. One full discharge-to-shutdown followed by a complete charge resets the coulomb counter and aligns the fuel gauge IC to the actual discharge curve of the replacement cell.
Phone warm near the battery door during the first few charges
A new Li-ion cell has slightly higher internal impedance than a cell that has completed its first few cycles. The Xperia Arc's charge IC pushes a constant current into this higher-impedance cell, and the resistance converts some of that energy to heat rather than stored charge. This is normal during the first two to three charge cycles and settles as the cell's impedance drops. If the handset remains noticeably warm past the fifth charge cycle, check that the charge port is clean — debris in the micro-USB port on the LT15i forces the charge IC to work harder to maintain current, which amplifies heat at the battery.