Acer BAT-M10 Liquid S2 Replacement Battery 3.8V 3000mAh

Acer Liquid S2 / S520 — 3.8V Li-Polymer Replacement Battery (BAT-M10)

This is a 3.8V, 3000mAh Li-Polymer replacement battery for the Acer Liquid S2, S520, Liquid Jade S2, and S58A smartphones. It matches OEM part numbers BAT-M10 and KT.0010S.007. Physical dimensions are 96.86 × 56.66 × 4.35 mm — confirm these against your existing cell before installing.

• Liquid S2 and S520 platform fit: These models share the same battery bay geometry, connector pinout, and BMS handshake protocol. One cell covers the full range listed without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Liquid S2 platform. The BMS accepted the cell, reported state-of-charge correctly after one full cycle, and thermal cutoff triggered within spec under sustained load.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before any high-current charge session pushes current into an uncalibrated cell.

Sudden shutdown at 20–30% on the Liquid S2 after cell swap

A new Li-Polymer cell has a slightly different voltage-versus-capacity curve than the aged cell the fuel gauge IC was calibrated against. When the modem fires or the screen brightness spikes, current draw pulls cell voltage down sharply — crossing the BMS undervoltage cutoff even though the OS still shows charge remaining. The device shuts off to protect the cell. One full discharge-charge cycle at standard rate resets the coulomb counter and aligns the fuel gauge to the new cell's actual curve. After that cycle, shutdowns at 20–30% stop.

Phone not powering on after the replacement battery sat in storage

Li-Polymer cells self-discharge in storage. If the cell voltage drops below approximately 2.5V, the BMS enters lockout mode and blocks all charge current to prevent damage. A standard charger will appear to do nothing — no charging indicator, no response. To recover the cell, connect the phone to a known-good wall adapter and leave it undisturbed for 15–30 minutes. The charge IC trickle-charges the cell at a low current rate to bring voltage back above the BMS re-enable threshold, typically around 3.0V, before resuming normal charging.