About this replacement
HP Envy X360 M6 — 15.4V Li-ion Replacement Battery (MB04XL)
This is a 15.4V lithium-ion battery rated at 3400mAh (52.36Wh), built to fit the HP Envy X360 M6 convertible laptop. It covers models including the M6-AQ105DX, M6-AQ003DX, and M6-AQ005DX, along with the broader M6 series. Cross-reference OEM part numbers MB04XL, HSTNN-UB6X, or TPN-W119/W120 before ordering.
- Envy X360 M6 platform fit: The M6 series runs a shared 15.4V four-cell battery rail across its convertible chassis. All covered models use the same connector pinout, BMS handshake protocol, and EEPROM charge data structure — which is why one part number covers the full lineup.
- Bench tested on actual hardware: We cycled this cell on an M6 chassis and verified the BMS initialised cleanly, the EEPROM flagged no fault codes, and charge current stepped down correctly at the 80% and 100% thresholds. No false over-temperature trips occurred during the test.
- Post-install calibration on the Envy X360 M6: After fitting, run the laptop down to hibernate-cutoff on battery alone — no AC adapter — then charge uninterrupted to 100%. This forces the fuel gauge IC to recalibrate against the new cell's actual capacity curve and clears the inaccurate health warning the BIOS throws after any cell swap.
BIOS reporting poor battery health immediately after fitting a new cell
The HP Envy X360 BIOS reads health status from EEPROM data stored during the previous cell's charge cycles. When a new cell goes in, that EEPROM register hasn't been written yet, so the BIOS flags the battery as degraded or unknown — even though the cell is fresh. This is not a fault with the replacement; it's a data gap. Running one full discharge-to-hibernate then an uninterrupted charge to 100% lets the battery controller rewrite the EEPROM registers with current cell data, and the health warning clears on the next boot.
Envy X360 M6 shutting down abruptly at 20–30% charge shown
This usually points to a voltage cliff — the cell drops below the BMS cutoff threshold under combined CPU and display load before the fuel gauge reaches zero. On a worn original battery, the internal resistance has risen enough that load spikes pull the cell voltage below roughly 12.5V momentarily, triggering an emergency shutdown. The OS-reported percentage is based on the fuel gauge estimate, not real-time cell voltage, so the two figures diverge under load. Run a full calibration cycle first — discharge to hibernate-cutoff, charge to 100% uninterrupted — and retest. If the shutdown persists on a brand-new cell, check for a BIOS update from HP that recalibrates the low-voltage threshold for the M6 platform.