Fujitsu LifeBook C1320 FPCBP115 Replacement Battery 10.8V 5200mAh

Fujitsu LifeBook C1320 Series — 10.8V Li-ion Replacement Battery (FPCBP115)

This is a 10.8V, 5200mAh (56.16Wh) Li-ion replacement battery for the Fujitsu LifeBook C1320, C1320D, C1321, and C1321D laptops. It replaces OEM part numbers FPCBP115 and FPCBP115AP. Install it when the original cell no longer holds enough charge to keep the laptop off AC power.

• C1320 and C1321 compatibility: Both the standard and D-suffix variants of these models share the same battery bay dimensions, connector pinout, and BMS communication protocol — which is why one cell covers all four configurations.
• Bench tested on actual hardware: We ran this cell through charge, discharge, and BMS handshake verification. The protection circuit tripped correctly at low-voltage cutoff and the BIOS recognised the pack without fault codes on the first boot.
• Post-install discharge cycle on the C1320: After fitting this battery, run the laptop on battery power until it hibernates from low charge — do not interrupt it. Then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after swapping cells.

Why the C1320 BIOS flags a new battery as poor health immediately after installation

The LifeBook C1320 BIOS reads battery health from EEPROM data embedded in the pack's protection circuit. When a new cell arrives, that EEPROM data does not match the usage history the BIOS expects from a known-good pack — so it raises a health warning straight away. This is a data mismatch, not a fault with the cell. One full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the BIOS to rewrite its learned capacity baseline against the new cell's actual chemistry.

LifeBook C1320 shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC still holds calibration data from the old, degraded cell. Under full CPU and display load, the new cell's actual voltage sits higher than the gauge expects at that percentage — then drops suddenly past the cutoff threshold before the OS can react. The laptop shuts down because the reported percentage and the real voltage diverge at high draw. Fix it by completing two to three full discharge-to-hibernate and charge-to-100% cycles, which forces the fuel gauge IC to recalibrate against the new cell's actual discharge curve.