About this replacement
Toshiba Portege X20W Series — 11.4V Li-Polymer Replacement Battery (PA5267U-1BRS)
This is an 11.4V 3650mAh (41.61Wh) Li-Polymer replacement battery for the Toshiba Portege X20W ultrabook series. It fits the X20W, X20W-D, X20W-D-10E, X20W-D-10Q, and over fifteen additional X20W-D variants. The OEM part number is PA5267U-1BRS.
- X20W-D series fit: All X20W-D variants share the same 11.4V three-cell Li-Polymer architecture, flat form factor, and BMS connector pinout. One replacement cell covers the entire sub-range without modification.
- Bench tested on actual hardware: We ran this cell on the X20W-D platform and logged BMS communication, charge acceptance, and cutoff behaviour. The BMS handshake completed on first connection and charge progressed normally from 0% through to 100%.
- Post-install calibration cycle: After fitting, run the laptop down to hibernate cutoff, then charge uninterrupted to 100% without using the machine. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
BIOS reporting battery health as poor immediately after replacement
The X20W-D BIOS reads health data stored in the outgoing cell's EEPROM and compares it against the new cell's reported state. A fresh cell with no charge history looks statistically abnormal to the firmware, so it flags the battery as degraded. This is not a fault with the replacement cell. Run one full discharge-to-hibernate, then a full uninterrupted charge to 100%, and the BIOS learn cycle will update its baseline. After one or two cycles the health warning clears.
Portege X20W shutting down at 20–30% charge shown
This happens when the fuel gauge IC is still calibrated to the old, degraded cell. The IC predicts remaining capacity based on historical discharge curves, and a new cell with higher actual capacity throws those curves off. The laptop hits what the firmware reads as a voltage cliff and triggers shutdown before the cell is genuinely empty. Run two full discharge-to-hibernate cycles, charging to 100% each time, and the fuel gauge IC will recalibrate against the new cell's actual voltage profile.