About this replacement
Fujitsu LifeBook N3400 Series — 14.4V Li-ion Replacement Battery (FPCBP120)
This 14.4V, 2200mAh (31.68Wh) Li-ion battery replaces the original cell in the Fujitsu LifeBook N3400, N3410, and N3430 notebooks. It matches the OEM voltage rail and connector pinout for each model in this series. Capacity figures come from product data — not web estimates.
- N3400, N3410, and N3430 compatibility: All three models share the same 14.4V battery bay, connector layout, and BMS handshake protocol. Fujitsu used the same FPCBP120 part across this entire series, with FPCBP119 and PCBP119AP as cross-reference OEM numbers for the same physical form factor.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a LifeBook N3400 unit. The BMS completed the handshake cleanly, the charge controller accepted the cell without fault codes, and the fuel gauge IC responded normally across multiple cycles.
- Post-installation discharge cycle: After fitting this battery, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that commonly appears after a cell swap on this series.
BIOS reporting poor battery health immediately after replacement
The LifeBook BIOS stores learned capacity data in EEPROM from the previous cell. When a new cell goes in, that stored data no longer matches actual chemistry behaviour, and the BIOS flags a health warning. This is not a fault with the replacement battery. Run one full discharge-to-hibernate followed by an uninterrupted full charge. After two to three cycles, the BIOS recalibrates against the new cell and the health warning clears.
Laptop shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC still holds calibration data from the degraded original cell. The percentage shown is calculated against old baseline values, so the display reads 25% while the actual cell voltage has already dropped below the safe cutoff threshold. The system shuts down to protect hardware — not because the new battery is faulty. Force a full discharge to hibernate, let the unit charge to 100% without interruption, and repeat once more. After two calibration cycles, the fuel gauge aligns to the new cell and the cutoff point shifts back to the correct low-voltage floor near 10.8V.