About this replacement
Panasonic Toughpad FZ-A2 / Toughbook CF-20 — 11.4V Li-ion Replacement Battery (CF-VZSU0QJS)
This is an 11.4V, 2600mAh (29.64Wh) Li-ion battery for the Panasonic Toughpad FZ-A2 and Toughbook CF-20 series. It replaces OEM part numbers CF-VZSU0QJS, CF-VZSU0QK, CF-VZSU0QW, CF-VZSU0QR, CF-VZSU0QQ, and CF-VZSU0QW-4. The physical cell fits the same bay and connects to the same BMS handshake points as the original.
- FZ-A2 and CF-20 platform compatibility: Both the Toughpad FZ-A2 and the Toughbook CF-20 detachable series share the same 11.4V cell format and BMS communication protocol. The connector pinout and EEPROM handshake are identical across all listed OEM part numbers, which is why a single replacement cell covers all variants.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the FZ-A2 platform. The BMS accepted the cell without fault codes, reported capacity within expected EEPROM tolerance, and the fuel gauge IC initialised correctly after the first calibration cycle.
- FZ-A2 battery learn cycle after swap: After installing, 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 appears after every cell swap. Skip this step and the fuel gauge may report incorrect percentage for weeks.
BIOS reporting poor battery health immediately after replacement
The Toughpad FZ-A2 stores battery health data in EEPROM on the original cell. When a new cell is installed, that EEPROM data does not match the new cell's actual chemistry profile, so the BIOS flags it as degraded or unknown. This is a data mismatch, not a fault with the replacement cell. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% lets the BIOS rewrite its battery learn data against the new cell. After two to three calibration cycles, the health indicator normalises.
FZ-A2 shutting down at 20–30% battery shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The OS reads a reported percentage, but the cell hits its low-voltage cutoff before the gauge reaches zero — especially under combined CPU and display load. The BMS trips at approximately 9.0V to protect the cells, which the OS shows as a sudden shutdown. Run two full discharge-to-hibernate cycles followed by full charges, and the gauge IC recalibrates its voltage-to-capacity map. After that, the displayed percentage and actual cutoff align.