BBK I269 Replacement Battery 3.7V 750mAh BK-B-26

BBK I269 / I188 — 3.7V Li-ion Replacement Battery (BK-B-26)

This is a 3.7V, 750mAh (2.78Wh) lithium-ion cell that replaces the original battery in the BBK I269 and I188 smartphones. It fits directly where the original BK-B-26, BK-B-26B, or BK-B-28 sat. If the phone shuts down unexpectedly, won't hold a charge, or the battery has swollen, this is the part to swap.

• I269 and I188 compatibility: Both models share the same battery bay dimensions (49.16 × 38.00 × 4.57mm), voltage rail, and connector pinout. The same OEM part numbers — BK-B-26, BK-B-26B, and BK-B-28 — cover both handsets, so one cell fits either device without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge passes on a BBK handset. The BMS responded correctly at both the low-voltage cutoff and the charge termination threshold. No false capacity readings on the first monitored cycle.
• Fuel gauge recalibration after install: On first use, disable fast charging if available and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before it locks in percentage thresholds — skipping this step causes the phone to report inaccurate percentages for days.

Sudden shutdown at 20–30% on a new cell

The fuel gauge IC in the I269 stores a discharge curve calibrated to the old cell. When a new cell arrives with a slightly different internal resistance profile, the IC reads voltage correctly but misjudges the remaining capacity. At around 3.6–3.65V the phone sees the modelled "empty" threshold and cuts power — even though the new cell still has charge left. One full slow discharge down to automatic shutdown, followed by a full charge to 4.2V, resets the coulomb counter and clears the erroneous cutoff point.

Phone warm near the battery during the first few charges

A new cell typically has higher internal impedance than a cell that has been cycled. The charge IC on the I269 pushes current into that higher impedance, and the extra resistance converts a small amount of energy to heat. This is normal for the first two to three charge cycles as the cell's impedance drops toward its rated value. If the phone stays warm beyond cycle three or gets too hot to hold comfortably, stop charging and check that the battery connector is fully seated — a partial connection forces the charge IC to work harder.