About this replacement
HP Spectre x360 13 Convertible — 11.1V Li-Polymer Replacement Battery (CP03XL)
This is an 11.1V, 4300mAh (47.73Wh) Li-Polymer replacement battery for the HP Spectre x360 13 Convertible series. It fits the Spectre x360 Convertible 13, 13t, and related convertible configurations covered under OEM part numbers CP03XL, CP03060XL, HSTNN-LB8E, 929066-421, and 929072-855. The cell dimensions are 264.95 x 128.00 x 4.05mm — physically identical to the factory unit.
- Spectre x360 13 platform fit: These models share the same three-cell Li-Polymer configuration, 11.1V nominal voltage rail, and matching BMS connector pinout — which is why a single part number spans all x360 13 convertible variants listed above.
- Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a Spectre x360 13 unit. The BMS handshake completed at first boot, BIOS recognised the cell, and charge control stepped through CC-CV phases without interruption.
- Post-install calibration on the Spectre x360: 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 this platform.
BIOS reporting battery health as poor after replacement on the Spectre x360
The Spectre x360 BIOS reads health data stored in the old cell's EEPROM and carries that degraded reading across to the new cell on first boot. The new cell has no charge history, so the fuel gauge IC has no reference point yet. This is not a fault with the replacement — it is a calibration gap. Running two full discharge-to-hibernate and charge-to-100% cycles gives the fuel gauge IC enough data to overwrite the stale EEPROM values and report accurately.
Spectre x360 shutting down at 20–30% charge shown on screen
This symptom means the cell voltage is hitting its low-cutoff threshold well before the OS fuel gauge reaches zero. Under combined CPU and display load, the Spectre x360 13 draws enough current to cause a voltage cliff — the cell drops below the BMS cutoff voltage while the OS still shows charge remaining. The fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. Run two full uninterrupted discharge cycles to hibernate-cutoff, then charge to 100% each time — the gauge recalibrates to the real cutoff point, typically around 10.5V per cell cluster.