Sony Ericsson Xperia Acro S 1253-4166.1 Replacement Battery 3.7V 1800mAh

Sony Ericsson Xperia Acro S / LT26w — 3.7V Li-Polymer Replacement Battery (1253-4166.1)

This is a 3.7V, 1800mAh lithium-polymer replacement battery for the Sony Ericsson Xperia Acro S (LT26w). It replaces OEM part numbers 1253-4166.1 and LIS1489EPRC. The Acro S is a 2012 Android smartphone with a water-resistant build, and this cell fits the original battery bay without modification.

• Acro S / LT26w compatibility: Both model identifiers share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The 56.44 × 53.10 × 5.10mm cell matches the original footprint exactly, so the NFC antenna layer and back cover seat correctly after installation.
• Bench tested on actual hardware: We ran this cell through charge and load cycles on the LT26w platform. The BMS communicated correctly with the phone's charge IC, accepted a full charge without thermal interruption, and held voltage above 3.5V under combined screen and modem load.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle from 100% down to automatic shutdown. This lets the fuel gauge IC map the new cell's discharge curve before reporting percentage to the OS — skipping this step causes erratic readings for the first several cycles.

Why the Acro S reports wrong battery percentage after a cell swap

The Xperia Acro S uses a coulomb-counter-based fuel gauge IC that builds its reference model from the original cell's charge and discharge history. When a new cell goes in, the IC is still calibrated to the old cell's internal resistance and voltage-capacity curve. Until it completes at least one full discharge-charge cycle, the percentage shown on screen is an estimate against the wrong model. The result is readings that jump — often showing 30% then cutting to shutdown, or sitting at 100% longer than expected. One full cycle from 100% to auto-shutdown and back to 100% resets the reference point.

Sudden shutdown at 20–30% on the replacement cell

This shutdown pattern is a voltage cliff, not a capacity problem. When the modem transmits or the screen brightness peaks, current draw spikes and cell voltage drops sharply — on an uncalibrated or high-impedance cell, voltage can fall below the 3.0V protection threshold in under a second, triggering a hard BMS cutoff before the percentage gauge catches up. The phone shuts off showing 20–25% because the gauge hasn't registered the voltage event. Run the phone down to automatic shutdown once, then charge uninterrupted to 100% — after that cycle the fuel gauge IC has a real discharge map and the premature shutdowns typically stop.