About this replacement
Sony VAIO PCG-GRX1P / PCG-R505 Series — 14.8V Li-ion Replacement Battery (PCGA-BP2R)
This is a 14.8V, 2600mAh (38.48Wh) Li-ion replacement battery for the Sony VAIO PCG-GRX1P and PCG-R505 series laptops. It covers models running OEM part numbers PCGA-BP2R, PCGA-BPZ51, PCGA-BPZ52, and PCG-Z505. If your original pack has degraded or fails to hold a charge, this cell replaces it directly.
- PCG-GRX1P and R505 series compatibility: These models share the same 14.8V battery rail, connector pinout, and BMS handshake protocol — one cell covers the full range without firmware conflicts or connector modifications.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on a VAIO PCG-R505 unit. The BMS accepted the cell without faulting, charge termination triggered correctly at full capacity, and protection circuitry responded normally to load changes.
- Post-install calibration on the PCG series: After fitting this battery, 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 on these Sony VAIO models.
BIOS reporting poor battery health immediately after replacement
Sony VAIO notebooks store battery health data in EEPROM on the original pack. When you swap cells, the BIOS reads stale data from its own memory and flags the new pack as degraded — even when the cell is fresh. This is a BIOS learn cycle issue, not a fault with the replacement cell. Run the battery from full to hibernate cutoff and back to 100% twice. After two full cycles, the BIOS recalibrates against the new cell's actual capacity and clears the health warning.
Laptop shuts down abruptly at 20–30% remaining
This is a voltage cliff failure. Under combined CPU and display load, the cell voltage drops faster than the fuel gauge IC can track. When cell voltage falls below the BMS cutoff threshold — typically around 11.1V on a 14.8V Li-ion pack — the system shuts down instantly, even though the OS still shows charge remaining. The fuel gauge is reading average voltage, not instantaneous load voltage. Run the calibration cycle above to resync the gauge, and check that power settings are not forcing maximum CPU performance while on battery.