Anycool W02 Compatible Battery 3.7V 1050mAh Li-ion

Anycool W02 — 3.7V Li-ion Replacement Battery

This is a 3.7V 1050mAh Li-ion battery for the Anycool W02 mobile phone. It replaces the original cell when the existing battery no longer holds a charge or fails entirely. At 53.00 x 33.90 x 5.60mm, it matches the physical footprint of the factory-installed unit.

• W02 platform fit: The W02 uses a compact single-cell Li-ion configuration at 3.7V nominal. The connector pinout and cell dimensions on this replacement match that layout directly — no adapter or modification needed.
• Bench tested on actual hardware: We cycled this cell through a full discharge and charge sequence, monitoring BMS cutoff behaviour at both ends. The protection circuit triggered correctly at low voltage and the cell accepted charge current without fault flags.
• Fuel gauge recalibration on first use: After fitting this replacement, disable any fast-charge option and run one complete discharge-to-charge cycle. This gives the fuel gauge IC time to map its readings against the new cell's actual discharge curve before high-current charging begins on an uncalibrated reference.

Why the W02 reports wrong battery percentage after a cell swap

The W02's fuel gauge IC stores a charge curve calibrated to the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The OS reads voltage from the gauge and translates it using the old curve, producing percentage figures that are off — sometimes significantly. One full discharge down to auto-shutdown followed by a complete charge cycle forces the IC to relearn the curve against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under the load of the modem or screen backlight — a voltage cliff the fuel gauge did not predict. The gauge shows 20–30% remaining but the cell voltage has already fallen below the BMS cutoff threshold under that transient load. It is not a faulty battery; it is a calibration gap. After one full reference cycle, the gauge recalibrates its cutoff estimate and the shutdowns stop. If they continue past two full cycles, check that the battery contacts are clean and seated flat.