Fujitsu FMV-BIBLO NB75K 14.4V Compatible Battery 0644180

Fujitsu FMV-BIBLO NB75K Series — 14.4V Li-ion Replacement Battery (FPCBP79)

This is a 14.4V, 4400mAh (63.36Wh) Li-ion battery for the Fujitsu FMV-BIBLO NB75K and related NB-series notebooks. It replaces OEM part numbers FPCBP79, FPCBP79AP, FPCBP83, FPCBP83AP, FM-41, FM-42, 0644180, and 0644190. The battery slots into the standard underside bay used across the NB75 and NB55 families.

• NB75 and NB55 series compatibility: These models share a 14.4V rail, the same physical connector pinout, and a common BMS handshake protocol — so one cell pack covers the full range from NB55L/T through NB75G, NB75H/T, and NB75K without modification.
• Bench tested on actual hardware: We cycled this pack through a full charge and controlled discharge on an NB75K chassis. The BMS engaged correctly at low-voltage cutoff, and the charge controller accepted the cell without throwing a fault code or refusing to negotiate the charging circuit.
• First-cycle recalibration on FMV-BIBLO notebooks: After installing, run the battery down until the laptop hibernates, then charge it uninterrupted to 100% without interrupting AC power. This forces the BIOS battery learn cycle to reset against the new cell's actual capacity and clears the inaccurate health warning that appears after every cell swap on FMV-BIBLO hardware.

BIOS reporting poor battery health immediately after fitting a new cell

The FMV-BIBLO BIOS reads health data from EEPROM embedded in the battery pack — it does not measure the new cell directly on first boot. The old pack's EEPROM data lingers in the system's memory until a full learn cycle flushes it. Run one complete discharge to hibernate cutoff, then a single uninterrupted charge to 100%. After that cycle, the BIOS re-reads the cell's actual state and the health warning clears.

Laptop shuts down at 20–30% charge shown on screen

This is a voltage cliff issue — not a faulty cell. The fuel gauge IC was calibrated against the old, degraded cell and now misreads remaining capacity under combined CPU and display load. When actual cell voltage drops below the cutoff threshold, the system shuts down even though the gauge still shows charge remaining. Run two full discharge-to-hibernate and charge-to-100% cycles to recalibrate the fuel gauge IC against the new cell's voltage curve. After calibration, the gauge should track accurately down to approximately 3.0V per cell before cutoff.