WINNER WG1 Replacement Battery 3.7V 1200mAh Li-ion

WINNER WG1 / WG8 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1200mAh Li-ion cell for the WINNER WG1 and WG8 smartphones. It replaces the original battery when capacity has degraded and the phone can no longer hold a usable charge. Physical dimensions are 53.00 × 34.00 × 5.70mm — measure your original before fitting.

• WG1 and WG8 compatibility: Both models share the same battery bay dimensions, voltage rail, and connector pinout, so one cell covers either handset without modification.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the WG1 platform. The BMS accepted the charge profile correctly and protection circuits tripped as expected at low-voltage cutoff.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its discharge curve against the new cell before high-current charging begins on an uncalibrated state-of-charge register.

Sudden shutdown at 20–30% on the WINNER WG1 after a cell swap

This happens because the fuel gauge IC still holds the discharge curve from the old, degraded cell. The new cell has a steeper voltage cliff under modem or screen load, so the phone hits the hardware undervoltage cutoff well before the OS percentage reaches zero. The phone reads 25% but the cell has already dropped below the safe floor under load. One full discharge-charge cycle with the screen on forces the coulomb counter to relearn the new cell's actual voltage curve.

Phone won't power on after the replacement battery sat in storage

Li-ion cells self-discharge in storage, and if voltage drops below approximately 2.5V per cell, the BMS enters lockout to prevent damage. The phone will show nothing when you press the power button — no boot logo, no charging animation. Connect the phone to a low-current charger (a standard 5V wall adapter, not a fast charger) and leave it for 20–30 minutes before attempting to power on. Once the cell recovers above 3.0V, the BMS re-enables the output rail and the phone will respond normally.