HB416492EFW Honor X8 4G Replacement Battery 3.87V 4000mAh

Honor X8 4G (TFY-LX1 / LX2 / LX3) — 3.87V Li-Polymer Replacement Battery (HB416492EFW)

This is a 3.87V, 4000mAh (15.48Wh) Li-Polymer cell built to fit the Honor X8 4G smartphone. It replaces OEM part HB416492EFW across the TFY-LX1, TFY-LX2, and TFY-LX3 hardware variants. If your X8 4G shuts off unexpectedly or won't hold a charge through a normal day, this is the direct cell swap.

• TFY-LX1, LX2, LX3 compatibility: All three regional variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell fits all three. No wiring adapters or bracket modifications needed.
• Bench tested on actual hardware: We ran this cell on an X8 4G unit and confirmed the BMS accepted the charge cycle without fault codes, cell voltage held stable under display and modem load, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — preventing percentage jumps and premature low-battery warnings.

Why the X8 4G shuts down suddenly at 20–30% after a battery swap

The X8 4G uses a coulomb counter tied to the fuel gauge IC, which was calibrated to the discharge curve of the original cell. After a cell swap, the stored curve no longer matches the new cell's actual voltage-versus-capacity profile. When the modem fires a high-current burst — during a call or data sync — the new cell's voltage dips below the shutdown threshold even though the gauge still reads 20–30%. One full discharge-to-shutdown followed by a full charge resets the coulomb counter and eliminates this cliff. After that cycle, the reported percentage tracks actual cell state accurately.

Honor X8 4G not powering on after sitting in storage

Li-Polymer cells self-discharge roughly 2–3% per month in storage. If the phone sat unused for several months, the cell voltage may have dropped below 2.5V per cell — the threshold where the BMS locks out to prevent damage. The device will show nothing when you press the power button. Connect it to a wall charger, not a PC port, and leave it for 20–30 minutes before attempting to power on; a wall adapter delivers enough current to wake the BMS from lockout. If the charge icon appears and the phone boots, let it reach 100% before the first full use cycle.