HW03XL Replacement Battery for HP Pavilion 15 11.34V 3400mAh

HP Pavilion 15 EG0073CL / 15-EG0000 — 11.34V Li-Polymer Replacement Battery (HW03XL)

This is an 11.34V, 3400mAh (38.56Wh) Li-Polymer replacement battery for the HP Pavilion 15 EG0073CL and the broader Pavilion 15-EG0000 series. It replaces OEM part numbers HW03XL, HSTNN-IB90, L96887-1D1, L96887-421, and L97300-005, among others. If your original pack no longer charges or causes the laptop to run only on AC power, this cell restores portable operation.

• Pavilion 15-EG0000 series compatibility: These models share a three-cell Li-Polymer architecture on the same 11.34V rail with a standardised connector and BMS communication protocol. The HW03XL part number covers the full EG0000 production run, so connector alignment and BMS handshake carry over without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Pavilion 15-EG unit. The BMS negotiated correctly with the EC, charge current tapered at the expected 4.35V per cell ceiling, and no fault codes were logged in the battery EEPROM during the test sequence.
• Post-install calibration on the EG0000 platform: After fitting this cell, run the laptop down to hibernate-cutoff under normal load, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell data and clears the inaccurate health warning that appears in HP Support Assistant after every cell swap.

BIOS reporting poor battery health immediately after fitting a new HW03XL

The HP Pavilion EC reads health data from the battery EEPROM, which on a new cell carries factory default values rather than learned charge data for your specific unit. The BIOS interprets this as degraded capacity and flags a health warning in HP Support Assistant. This is not a fault with the replacement cell — it reflects a mismatch between stored EEPROM state and actual cell chemistry. One full discharge-to-hibernate followed by an uninterrupted charge to 100% rewrites the learned values and clears the warning on the next boot.

Laptop shuts down abruptly when the fuel gauge still shows 20–25% remaining

This happens when the fuel gauge IC has not yet calibrated its discharge curve against the new cell. The IC uses impedance tracking to estimate remaining capacity, and with a fresh cell it initially maps the old cell's voltage cliff onto the new chemistry. The result is an early shutdown at what appears to be 20–25%, even though the cell still holds charge. Run two to three full discharge-to-hibernate and full-charge cycles, and the fuel gauge IC recalibrates — shutdowns should stop occurring above a true low-voltage cutoff of approximately 9.9V system-side.