Poco C55 Compatible Battery BN5K 3.82V 4900mAh

Poco C55 (22127PC95I) — 3.82V Li-Polymer Replacement Battery (BN5K)

This is a 3.82V, 4900mAh (18.72Wh) lithium-polymer cell built to replace the BN5K battery in the Poco C55 (model 22127PC95I). It fits directly into the C55 chassis and connects to the same ribbon connector and BMS interface as the original. Dimensions are 96.80 × 64.50 × 4.30mm — verify your old cell matches before ordering.

• C55 and 22127PC95I fitment: Both model identifiers reference the same hardware revision. The BN5K connector, cell dimensions, and BMS handshake protocol are identical across both designations — one cell covers both.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a C55 unit. The BMS accepted charge handshake without fault codes, and the protection circuit tripped correctly at the low-voltage threshold rather than allowing the cell to drop below safe operating range.
• 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 map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes load into an uncalibrated cell.

Sudden shutdown at 20–30% on the Poco C55 after a cell swap

This is the most reported symptom after fitting a replacement BN5K. The fuel gauge IC on the C55 was calibrated to the old cell's internal resistance and discharge curve. When the new cell hits a voltage level the IC doesn't recognise as critical, the phone drops load abruptly rather than stepping down gracefully. Run one full uninterrupted discharge to around 3.55V open-circuit rest, then charge to 100% without interruption. After two complete cycles the gauge IC recalibrates and the shutdowns stop.

USB fast charge not accepted on the first cycle after replacement

The C55's charge IC negotiates fast-charge current based on cell impedance reported by the BMS. A new BN5K cell has higher initial impedance than a broken-in cell, so the charge IC may fall back to standard 5V/1A on the first session rather than stepping up to the higher current tier. This is not a fault — it resolves after the first full cycle as the cell's impedance settles. If fast charge still won't engage after two cycles, check that the cable supports the correct current rating and reseat the battery connector at the board-side ZIF socket.