HP Business Notebook NC4400 381373-001 10.8V Replacement Battery

HP Business Notebook NC4400 / TC4200 / TC4400 — 10.8V Li-ion Replacement Battery (381373-001)

This is a 10.8V, 4400mAh (47.52Wh) Li-ion replacement battery for the HP Business Notebook NC4400, TC4200, TC4400, and 4200 series. It matches OEM part numbers 381373-001, 383510-001, HSTNN-IB12, and PB991A. The physical dimensions are 125.60 × 72.40 × 19.90mm — confirm your bay dimensions before ordering if you are unsure of your exact model variant.

• NC4400 / TC4200 / TC4400 platform fit: These models share the same battery bay dimensions, 10.8V power rail, and HSTNN connector pinout. One cell works across the entire series because HP used a common BMS handshake on this mid-2000s business notebook line.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the NC4400 platform. The BMS communicated normally with the system board, charge termination triggered correctly at full capacity, and no thermal events occurred across the test run.
• Post-install calibration on the NC4400: After fitting this battery, run the laptop down to hibernate cutoff on battery power alone — no AC adapter — then charge it uninterrupted to 100%. This forces the BIOS to reset its battery learn cycle against the new cell data and clears the inaccurate health warning that appears after every cell swap on this platform.

BIOS reporting poor battery health immediately after fitting a new cell

The NC4400 BIOS reads health data stored in the battery's EEPROM and compares it against a learned baseline from the previous cell. A new battery carries different EEPROM values, so the BIOS flags it as degraded before any learn cycle has run. This is a data mismatch, not a fault with the new cell. Run one full discharge-to-hibernate followed by an uninterrupted charge to 100% — after that cycle, the BIOS recalibrates and the health warning clears.

Laptop shuts down at 20–30% charge shown on the gauge

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The gauge reports percentage based on the old cell's discharge profile, so it reads 25% while the cell voltage has already dropped below the cutoff threshold under full CPU and display load. The system shuts off to protect the cell — not because the battery is faulty. Two to three full discharge-and-charge cycles let the fuel gauge IC re-map the voltage curve accurately. After calibration, cutoff should occur below 5% at no lower than 9.0V under load.