NU02XL HP Pavilion M1 Replacement Battery 7.7V 4300mAh

HP Pavilion M1-U Series — 7.7V Li-ion Replacement Battery (NU02XL)

This is a 7.7V, 4300mAh (33.11Wh) Li-ion battery for the HP Pavilion M1, M1-U, and M1-U001DX notebooks. It slots into the same bay as the original NU02XL and restores battery-powered operation to units with degraded or failed cells. OEM cross-references include HSTNN-UB6U, TPN-W117, 843535-541, and 844200-850.

• Pavilion M1-U platform fit: The M1-U line shares a single battery bay spec — 7.7V nominal rail, same connector pinout, and the same BMS handshake protocol across the M1, M1-U, and M1-U001DX variants. One cell fits the full range without adapter or modification.
• Bench tested on actual hardware: We ran this cell on an M1-U001DX unit and logged the BMS charge cycle from 0% to full. Charge current tapered correctly at the CV stage, and the protection circuit tripped cleanly at the low-voltage floor — no abnormal cutoffs or communication errors during the test.
• Post-install calibration on the M1-U: After fitting this cell, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. The Pavilion M1 BIOS uses a battery learn cycle to map cell capacity — skipping this step leaves the fuel gauge IC working off old data, which causes the inaccurate health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after fitting the NU02XL

The HP Pavilion M1 BIOS reads battery health from EEPROM data written by the previous cell. When a new cell goes in, that stored data doesn't match the new cell's charge curve — so the BIOS flags it as degraded before it has run a single cycle. This is not a fault with the replacement cell. Run one full discharge-to-hibernate, then a complete uninterrupted charge, to let the BIOS overwrite the stale EEPROM health data. After two to three cycles the health status in HP Support Assistant should update to normal.

Pavilion M1 shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The IC is still referencing voltage thresholds from the worn-out original cell, so it calls shutdown too early. Under combined CPU and display load, the voltage drop looks steeper than the IC expects, and it triggers a protective shutdown before the cell is actually empty. Run two full discharge-to-hibernate cycles and charge back to 100% each time — by the second full cycle the fuel gauge IC recalibrates and the reported percentage aligns with actual remaining charge.