About this replacement
HP EliteBook 830 G9 / 840 G9 / 845 G9 / 860 G9 — 11.58V Li-Polymer Replacement Battery (WP03XL)
This is an 11.58V, 3150mAh (36.48Wh) Li-Polymer replacement battery for the HP EliteBook 830 G9, 840 G9, 845 G9, and 860 G9 ultrabook laptops. It replaces OEM part numbers WP03XL, HSTNN-LB8W, HSTNN-OB2J, M64305-421, and M73466-005. The cell fits the slim chassis shared across these four EliteBook G9 models.
- EliteBook G9 series fit: The 830, 840, 845, and 860 G9 all share the same battery bay geometry, connector pinout, and BMS handshake protocol — one cell covers all four models without modification.
- Bench tested on actual hardware: We ran this cell through charge, discharge, and BMS communication checks on an EliteBook 840 G9. The BMS authenticated correctly, voltage held steady under CPU and display load, and no charge faults were triggered.
- Post-swap BIOS learn cycle: After fitting this cell, run the laptop down 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 EliteBook G9 units.
BIOS reporting battery health as poor immediately after replacement
The HP EliteBook G9 BIOS reads EEPROM data stored on the outgoing cell and compares it against the new one. When that data does not match, the BIOS flags health as unknown or poor — even with a fully functional new cell installed. This is not a fault with the replacement battery. Run one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100% and the BIOS recalibrates against the new cell's actual charge curve. After one or two full cycles, the health indicator clears and reports accurately.
Laptop shuts down at 20–30% charge remaining after battery swap
This happens because the fuel gauge IC on the motherboard is still calibrated to the old cell's voltage curve. The new cell hits a voltage cliff under combined CPU and display load at a point the firmware reads as 20–30% remaining. The system interprets this as a critically low voltage and cuts power to protect the hardware. Fix this by completing two full discharge-to-hibernate cycles with an uninterrupted charge to 100% between each — after that, the fuel gauge IC maps correctly to the new cell and the false low-battery shutdowns stop.