BBK VIVO Y55 Replacement Battery B-B1 3.85V 2700mAh

BBK VIVO Y55 Series — 3.85V Li-Polymer Replacement Battery (B-B1)

The B-B1 is a 3.85V, 2700mAh (10.4Wh) lithium-polymer cell that fits the VIVO Y55, Y55A, and Y55L smartphones. It slots into the same footprint as the factory cell at 83.10 × 61.20 × 3.20 mm. Use this when the original battery no longer holds charge or causes unexpected shutdowns.

• Y55, Y55A, Y55L compatibility: All three models share the same internal battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers the full platform without modification.
• Bench tested on actual hardware: We cycled the B-B1 through full discharge and recharge on a Y55 unit. The BMS accepted the cell on first insertion, charge current ramped correctly, and the protection circuit triggered cleanly at the low-voltage cutoff threshold.
• First-cycle fast-charge hold: After installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.

Sudden shutdown at 20–30% on the VIVO Y55 after a cell swap

The VIVO Y55 fuel gauge IC holds a learned discharge curve from the original cell. A new cell with a different internal resistance profile hits a voltage cliff earlier than the IC expects, cutting power before the displayed percentage reaches zero. This is a calibration gap, not a faulty battery. Run two full discharge-charge cycles at standard charge rate and the coulomb counter will converge on the new cell's actual curve.

Phone won't power on after the B-B1 sat in storage

Li-polymer cells stored below 2.5V trigger a BMS lockout that blocks normal boot. The VIVO Y55 charge IC cannot start if the cell voltage is too low to power the protection circuit. Connect the phone to a wall charger — not a PC USB port — and leave it for 15–20 minutes without attempting to power on. Once the cell climbs above approximately 3.0V, the BMS releases and the phone will boot normally.