About this replacement
Sony VAIO VGN-AW Series — 11.1V Li-ion Replacement Battery (VGP-BPS21)
This 11.1V, 8800mAh (97.68Wh) Li-ion battery replaces the VGP-BPL21, VGP-BPS21, VGP-BPS21A, VGP-BPS21B, and VGP-BP21A cells used in the Sony VAIO VGN-AW series. It fits models including the VGN-AW41JF, VGN-AW41MF, VGN-AW41XH, VGN-AW41ZF, and over 280 additional VAIO AW variants. Voltage, connector, and BMS handshake all match the original Sony specification.
- VAIO AW series fit: Every model in the VGN-AW line shares the same 11.1V battery rail, three-pin connector, and SMBus BMS protocol. That common architecture is why one cell covers the full AW range — the BIOS negotiates charge parameters over the same data line regardless of the specific AW suffix.
- Bench tested on actual hardware: We ran this cell on a VGN-AW41 unit. The BMS handshake completed on first insertion, the BIOS accepted the pack without error, and the charge controller cycled from 0% to full capacity without interruption or thermal flag.
- BIOS learn cycle after install: After fitting this battery, run the laptop on battery only until it hibernates at the low-voltage cutoff, then charge it uninterrupted to 100%. This forces the VAIO BIOS to run its battery learn cycle against the new cell and clears the false "poor health" warning that almost always appears after a cell swap on this platform.
Why the VAIO AW BIOS reports poor battery health immediately after a cell swap
The VGN-AW BIOS reads battery health from EEPROM data stored inside the battery pack — not from live voltage measurements. When a new cell arrives, the EEPROM holds factory-default values that the BIOS interprets as a depleted or degraded pack. This is not a fault with the replacement cell. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% rewrites the fuel gauge IC's reference data and brings the BIOS health indicator back to normal. Until that cycle completes, the health warning is meaningless.
Laptop shuts down at 20–30% remaining on battery
This usually happens when the fuel gauge IC hasn't yet calibrated against the new cell's actual voltage curve. Under full CPU and display load, the battery voltage drops sharply in the lower charge band — faster than the uncalibrated gauge predicts. The BIOS hits its low-voltage cutoff before the displayed percentage reaches zero, so the machine shuts off abruptly. Run two full discharge-to-hibernate and full-recharge cycles without interruption. After the second cycle, the fuel gauge IC maps the new cell accurately and the early shutdown stops. If it persists past three cycles, check that the battery voltage at shutdown is above 9.0V using a multimeter on the pack terminals.