About this replacement
HP Spectre X360 15 — 11.55V Li-Polymer Replacement Battery (PG03XL)
This is an 11.55V, 5600mAh (64.68Wh) lithium-polymer battery for the HP Spectre X360 15 convertible laptop. It fits the AP011DX and AP000 series alongside 85+ additional Spectre X360 15 configurations. OEM cross-references include HSTNN-LB7C, 831532-421, 831532-422, and TPN-Q168.
- Spectre X360 15 platform fit: All covered models share the same 11.55V three-cell Li-Polymer architecture, physical connector pinout, and BMS handshake protocol. The PG03XL part number is the unifying OEM identifier across the AP000 series chassis variants.
- Bench tested on actual hardware: We ran this cell on the Spectre X360 15 platform and monitored BMS communication across charge and discharge cycles. The protection circuit responded correctly at both low-voltage cutoff and full-charge termination with no fault flags triggered.
- First-cycle conditioning on the Spectre X360 15: After installing, 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 routinely appears after a cell swap on this platform.
Why the Spectre X360 15 BIOS flags a new battery as poor health
The HP EC reads EEPROM data written by the original factory cell. When a replacement cell arrives, that stored charge history doesn't match the new cell's actual state, so the firmware rates health as degraded or unknown. This is a data mismatch — not a physical fault with the replacement. Running the battery learn cycle (full discharge to hibernate, then uninterrupted charge to 100%) rewrites the EEPROM baseline against the new cell. After one or two full cycles, the BIOS health reading normalises.
Spectre X360 15 shutting down at 20–30% shown on the gauge
This happens when the fuel gauge IC hasn't calibrated against the new cell's actual voltage curve. The gauge was mapped to the old cell's discharge profile, so it loses track of true remaining capacity under CPU and display load. As voltage drops sharply under combined load — the voltage cliff — the system shuts down before the displayed percentage reaches zero. Run two full discharge-to-hibernate and full-charge cycles to let the fuel gauge IC re-anchor its curve to the replacement cell; the cutoff point should shift to below 5% displayed.