HP EliteBook x360 1040 G7 HK04XL Replacement Battery 7.72V 9050mAh

HP EliteBook x360 1040 G7 — 7.72V Li-Polymer Replacement Battery (HK04XL)

This is a 7.72V, 9050mAh (69.87Wh) lithium-polymer replacement battery for the HP EliteBook x360 1040 G7 convertible notebook. It fits models including the 226Z2PA, 119Y7EA, 204P1EA, and 8WA61AV, among others. OEM part numbers HK04XL, HSTNN-IB9J, L83796-171, and L84352-005 all cross-reference to this cell.

• EliteBook x360 1040 G7 compatibility: All G7 1040 variants on this list share the same 7.72V two-cell Li-Polymer architecture, connector pinout, and BMS handshake protocol — that's why one cell covers the full model range without firmware or connector differences.
• Bench tested on actual hardware: We ran this cell through charge, discharge, and BMS communication checks on the G7 platform. The protection circuit responded correctly to charge termination and low-voltage cutoff. No fault codes triggered during the test cycle.
• First-cycle recalibration on the G7: After fitting, run the battery down until the laptop hibernates, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that almost always appears after a cell swap on this platform.

BIOS reporting poor battery health immediately after fitting the new cell

The HP BIOS reads health data stored in the old cell's EEPROM and flags the replacement as degraded because it doesn't yet have a charge history. This is an EEPROM mismatch, not a fault with the new cell. Running one full discharge-to-hibernate followed by a complete uninterrupted charge allows the BIOS battery learn cycle to rewrite that data against the new cell. After two to three cycles, the health status normalises and the warning clears.

Laptop shutting down at 20–30% shown on the fuel gauge

This happens when the fuel gauge IC hasn't calibrated against the new cell's actual discharge curve yet. The gauge was mapped to the old, degraded cell — so what it reports as 25% is actually the voltage cliff of a fresh cell under full CPU and display load. The fix is the same calibration cycle: discharge fully to hibernate cutoff, then charge to 100% without interruption. Repeat two to three times and the gauge will track the new cell accurately, typically stabilising above 7.4V at the point where it previously cut out.