TCL A860 Replacement Battery 3.7V 1750mAh Li-ion

TCL A860 / A998 / W989 / A968 Series — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1750mAh Li-ion cell for the TCL A860, A998, W989, and A968 smartphones. It fits directly in place of the original cell using the same connector and footprint. Use the capacity figure from this listing — 1750mAh — not third-party sources.

• A860 / A998 / W989 / A968 platform fit: These models share the same battery bay dimensions (64.60 × 43.95 × 5.10mm), connector pinout, and charge IC handshake. One cell covers all four without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the A860 platform. The BMS accepted the charge IC handshake without flagging an error, and voltage held steady through a full screen-on load cycle.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% on standard current. This gives the fuel gauge IC one full cycle against the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the TCL A860 after a cell swap

This happens because the fuel gauge IC is still referencing the old cell's discharge curve. When the phone draws high current — modem, GPS, or screen at full brightness — the new cell's voltage drops faster than the IC expects. The phone interprets that as a critically low cell and cuts power before the percentage display catches up. One full discharge-charge cycle on standard current lets the coulomb counter re-map to the actual curve. After that cycle, shutdowns at 20–30% stop.

USB charging not starting after the phone sat in storage with a flat battery

If a Li-ion cell drops below approximately 2.5V per cell during long storage, the BMS locks out to prevent an unsafe charge into an over-discharged cell. The phone shows no charging indicator and will not power on. Connect to a 5V USB source and leave it for 20–30 minutes without attempting to power on — the BMS uses a low-current trickle path to bring the cell back above the lockout threshold. Once voltage recovers above roughly 3.0V, normal charging resumes and the boot sequence will proceed.