About this replacement
HP ZBook 15 G5 — 15.4V Li-ion Replacement Battery (VX04XL)
This is a 15.4V, 5600mAh (86.24Wh) lithium-ion replacement battery for the HP ZBook 15 G5 mobile workstation. It fits the ZBook 15 G5 series, including models 2YX00AV, 3AX02AV, 3AX03AV, and over 24 additional variants. The OEM part numbers covered include VX04XL, HSN-Q13C, HSTNN-IB8F, L05766-855, and 4ME79AA.
- ZBook 15 G5 platform fit: All ZBook 15 G5 variants share the same 15.4V four-cell battery architecture, connector pinout, and BMS handshake protocol. The SMBus communication lines are identical across the G5 series, so the BIOS recognises this cell without flashing or modification.
- Bench tested on actual hardware: We ran this battery on a ZBook 15 G5 under sustained CPU and GPU load. The BMS held the voltage rail above 14.8V throughout the discharge curve and tripped the low-voltage cutoff at the correct threshold without any spurious shutdowns.
- Post-install calibration cycle: After fitting this battery, run the laptop down to hibernate cutoff under real workload — not just screen-on idle — then charge uninterrupted to 100%. This forces the ZBook's EC firmware to relearn the cell's actual capacity curve and clears the inaccurate health warning that appears after every cell replacement.
Why the ZBook 15 G5 shuts down at 20–30% remaining after a battery swap
The ZBook 15 G5 uses an embedded controller that maps voltage thresholds against the old cell's discharge curve stored in EEPROM. A new cell with a different internal resistance profile reaches the EC's learned shutdown voltage earlier than the gauge expects. Under full CPU plus dedicated GPU load, the voltage sags faster than the OS fuel gauge can track. The fix is a full battery learn cycle: discharge to hibernate under load, then charge to 100% without interruption — after two cycles the EC recalibrates its threshold mapping to the new cell.
BIOS reporting battery health as "Poor" or "Unknown" immediately after installation
The HP BIOS reads health data from the battery's EEPROM at POST. A replacement cell ships with EEPROM counters at zero, which the firmware interprets as a degraded or unrecognised unit. This is a firmware read artefact — not a fault with the cell itself. Boot into HP PC Hardware Diagnostics or the BIOS battery check utility, run the battery learn cycle once, and the health status updates to reflect the actual cell state. After calibration, the BIOS should report voltage at or above 15.2V on a full charge.