About this replacement
HP Pro x360 Fortis 11 G9 — 11.4V Li-Polymer Replacement Battery (AN03XL)
This is an 11.4V, 3600mAh (41.04Wh) lithium-polymer battery for the HP Pro x360 Fortis 11 G9 convertible notebook. It replaces OEM part numbers AN03XL, HSTNN-OB2K, L173474-005, and TPN-DM0M. The cell fits both the standard Pro x360 Fortis 11 G9 and the G9 Notebook PC variant.
- Pro x360 Fortis 11 G9 compatibility: HP tied the AN03XL fitment to a shared three-cell, 11.4V bus across the entire Fortis 11 G9 lineup. The connector pinout and BMS handshake protocol are identical across chassis revisions, so this cell works in both the standard and Notebook PC configurations without modification.
- Bench tested on actual hardware: We ran this cell on a Pro x360 Fortis 11 G9 and confirmed the BMS negotiation completed correctly, charge termination triggered at the right voltage, and the protection circuit responded normally to a simulated load spike from the processor.
- Post-install discharge cycle on the Fortis 11 G9: After fitting this cell, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. The Fortis 11 G9's BIOS battery learn cycle resets on that first full cycle — skipping it leaves the fuel gauge reporting inaccurate capacity and the BIOS flagging poor battery health for weeks.
BIOS reporting poor battery health immediately after fitting a new AN03XL
The HP Fortis 11 G9 BIOS reads health data stored in the battery's EEPROM. A replacement cell ships with factory EEPROM values that the BIOS hasn't yet validated against real charge cycles on your hardware. Until the learn cycle runs, the BIOS treats the mismatch as a fault and flags the battery as degraded. This is not a defective cell — it is an unlearned one. Run a full discharge to hibernate-cutoff and one uninterrupted charge to 100%, and the health warning clears.
Laptop shutting down at 20–30% charge shown after battery replacement
This happens when the fuel gauge IC hasn't calibrated against the new cell's actual voltage curve. The gauge is still using the old cell's discharge profile, so it misreads the remaining capacity under CPU and display load — the voltage cliff arrives earlier than the percentage shown suggests. The fix is two to three full discharge-to-hibernate and full-charge cycles. After calibration, the percentage reading and the actual cutoff voltage align, typically around 10.8V at low-charge warning.