About this replacement
Sony Xperia 5 — 3.85V Li-Polymer Replacement Battery (LIP1705ERPC)
This is a 3.85V, 2900mAh Li-Polymer replacement battery for the Sony Xperia 5 smartphone, including model variants J9210, SOV41, and 901SO. It replaces the original LIP1705ERPC cell when the factory battery holds less charge, shuts down unexpectedly, or no longer accepts a full charge. Dimensions are 78.80 × 45.35 × 5.00mm — confirm clearance before installation.
- Xperia 5 variant compatibility: The J9210, SOV41, and 901SO share the same physical battery bay, connector pinout, and BMS handshake protocol as the global Xperia 5. All variants draw from the same 3.85V voltage rail, so one cell covers the full range without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Xperia 5 platform. The BMS accepted the handshake on the first connection, charge current ramped correctly through CC/CV stages, and the fuel gauge IC tracked state-of-charge without error flags.
- First-cycle fast charge protocol: On first use after installation, disable fast charging for one complete discharge-charge cycle. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes into an uncalibrated state-of-charge window.
Why the Xperia 5 reports wrong battery percentage after a cell swap
Sony's fuel gauge IC builds a discharge model against the specific cell it was calibrated on. When you swap in a new cell, the IC is still reading against the old curve — so it can report 40% when the cell is actually near 15%. The fix is one full discharge to auto-shutdown followed by an uninterrupted charge to 100% with fast charging off. After that cycle, the coulomb counter resets and the percentage tracks accurately. If the gauge still drifts after two cycles, check that the battery connector is fully seated — a loose pin introduces resistance that skews voltage readings.
Sudden shutdown at 20–30% on the new cell
This is a voltage cliff — not a capacity issue. Under peak load from the modem, display, or a CPU burst, the cell voltage drops sharply and briefly falls below the BMS cutoff threshold, triggering an emergency shutdown even though the OS still shows charge remaining. It happens most often during video calls or GPS navigation because both subsystems draw simultaneously. Run one full calibration cycle first — slow charge to 100%, full drain to shutdown. If shutdowns continue after calibration, check that cell voltage at rest reads above 3.7V before load is applied.