About this replacement
Fujitsu LifeBook T730 Series — 10.8V Li-ion Replacement Battery (CP422590-02)
This is a 10.8V, 4400mAh (47.52Wh) Li-ion battery for the Fujitsu LifeBook T730, T730TRNS, T731, and T901 convertible tablet-laptops. It replaces OEM parts CP422590-02, FMVNBP171, FPCBP200, FPCBP215, FPCBP280, and related variants. Install it when the original cell no longer holds a charge or the system refuses to run on battery power.
- T730 and T731 series compatibility: These models share the same voltage rail, physical connector, and BMS handshake protocol. The T730TRNS and T901 use the same battery bay dimensions and communication lines, so one cell covers the full group without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a T730 unit. The BMS negotiated correctly with the firmware, the charge controller accepted the cell without flagging an error, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
- First-cycle reset after installation: The T730's BIOS uses a battery learn cycle to track state-of-charge. After fitting this cell, discharge fully to hibernate cutoff, then charge uninterrupted to 100%. This clears the inaccurate health warning that appears after every cell swap and resets the learn cycle against the new cell's actual capacity.
Why the T730 shuts down at 20–30% remaining after a battery swap
The LifeBook T730 calculates remaining capacity using EEPROM data calibrated to the old cell. When a new cell is installed, the fuel gauge IC is still referencing the degraded discharge curve of the original battery. Under full CPU and display load — common in tablet mode with the touchscreen active — voltage drops faster than the BIOS expects, and it triggers a low-voltage shutdown while the gauge still shows charge remaining. Running a full discharge-to-hibernate followed by an uninterrupted full charge gives the fuel gauge IC the data it needs to remap the curve against the new cell. After two to three full cycles, the reported percentage and the actual cutoff point align.
BIOS reporting battery health as "poor" or "unknown" immediately after fitting a new cell
This happens because the BIOS reads health status from the battery's EEPROM, which stores historical charge data from the previous cell. A brand-new cell has no cycle history, so the BIOS interprets the blank or mismatched EEPROM values as a fault. It is not a defect in the replacement battery. Run the Fujitsu battery utility or allow one complete discharge-to-hibernate and recharge cycle — the BIOS learn cycle writes fresh baseline data and the health warning clears. If the warning persists after two full cycles, check that the BIOS is updated to the latest version available from Fujitsu's support portal for the T730.