BBK i267 Replacement Battery 3.7V 550mAh BK-BL-4C

BBK i267 / i508 / i518 Series — 3.7V Li-ion Replacement Battery (BK-BL-4C)

This is a 3.7V Li-ion cell rated at 550mAh (2.04Wh), replacing OEM part BK-BL-4C in BBK smartphones. It fits the i267, i508, i509, i518, and five additional models in the same series. When the original cell degrades and can no longer sustain voltage under screen or modem load, this is the direct swap.

• Cross-model fit — i267 through i518: These BBK models share the same physical footprint (53.00 × 34.00 × 4.80mm), connector pinout, and BMS handshake protocol — so one cell part number covers the full range without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on BBK series hardware. The BMS accepted the new cell without fault flags, and charge termination occurred correctly at 4.2V with no overcharge event logged.
• Fuel gauge recalibration on first use: On first use after installation, disable any fast-charge mode and complete one full discharge-to-charge cycle. This lets the phone's fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity defect. Under heavy modem or screen load, cell voltage drops faster than the fuel gauge predicts — the phone's protection circuit cuts power before the reported percentage reaches zero. It typically appears in the first five cycles on a fresh cell because the fuel gauge IC is still calibrated to the old cell's impedance curve. Run two full discharge-charge cycles without interruption and the fuel gauge will remap the cutoff threshold to the new cell. If it persists beyond three cycles, check that the battery connector is fully seated — a partial connection raises contact resistance and accelerates the voltage sag under load.

Phone not powering on after the replacement cell sat in storage

Li-ion cells shipped or stored at low state of charge can drop below 2.5V per cell, triggering BMS lockout — the pack will not respond to a normal power button press. Connect the phone to a wall charger and leave it for 15–20 minutes before attempting to power on; the charge IC applies a low-current trickle to bring the cell back above the BMS re-enable threshold. Do not use a USB port on a PC for this step — PC USB ports often cannot source enough current to wake a locked-out BMS. Once the charge indicator appears on screen, allow the battery to reach at least 3.0V before booting the device.