About this replacement
Sony VAIO Fit 11A — 7.2V Li-ion Replacement Battery (VGP-BPS42)
This is a 7.2V Li-ion battery rated at 3200mAh (23.04Wh), built to fit the Sony VAIO Fit 11A ultraportable notebook. It replaces part number VGP-BPS42 and fits SVF11N18CW, SVF11N14SCP, and SVF11N15SCP variants. Same voltage, same capacity, same physical connector as the original cell.
- VAIO Fit 11A series compatibility: These SVF11N models share a common battery bay geometry, connector pinout, and BMS handshake protocol. The 7.2V rail and 5.40mm slim-pack form factor are consistent across the range, so one cell fits all listed variants without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a VAIO Fit 11A unit. The BMS communicated correctly with the system board, charge acceptance was normal across the full cycle, and no fault codes appeared in the battery status register.
- First-cycle conditioning on the VAIO Fit 11A: After installing, let the battery discharge fully to hibernate-cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell and clears the inaccurate health warning that appears after every cell swap.
BIOS reporting poor battery health immediately after installing a new cell
The VAIO BIOS stores battery health data in EEPROM tied to the original cell's charge history. When a new cell is installed, the BIOS reads that stale data and flags health as poor before any calibration has occurred. This is a firmware read issue, not a fault with the replacement cell. Run one complete discharge-to-hibernate then a full uninterrupted charge cycle — the BIOS learn cycle will overwrite the old EEPROM data and the health flag will clear.
Laptop shuts down at 20–30% battery remaining shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's voltage curve. The displayed percentage is still mapped to the old cell's discharge profile, so the system hits a voltage cliff earlier than the gauge expects and cuts power to protect the board. It is not a defective cell. Run two to three full discharge-to-hibernate and charge-to-100% cycles — after calibration, the gauge will track the new cell accurately and shutdowns will stop occurring above 10V per cell group.