HP M38779-2B1 Laptop Replacement Battery 7.7V 4650mAh

HP M38779-2B1 — 7.7V Li-Polymer Replacement Battery (PD02XL)

This 7.7V, 4650mAh (35.81Wh) lithium-polymer battery replaces OEM part numbers M38779-2B1, M38780-005, PD02XL, and TPN-DB0H in compatible HP notebooks. It fits laptops that originally shipped with the PD02XL cell configuration. Install it when the original cell no longer holds a charge or the HP battery gauge reports degraded health.

• PD02XL platform compatibility: HP notebooks sharing this battery use a common 7.7V two-cell Li-Polymer rail with a TPN-DB0H controller handshake. The BMS communicates capacity and cycle data directly to the HP BIOS over SMBus — all four OEM part numbers map to the same electrical and physical specification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on compatible HP hardware. The BMS negotiated correctly with the BIOS, accepted a full charge to 35.81Wh, and did not trigger an overcurrent cutoff during normal load transitions.
• First-cycle calibration after install: After fitting this battery, run one full discharge to hibernate cutoff — do not force shutdown — then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after swapping the PD02XL

The HP BIOS reads health data stored in the old cell's EEPROM and compares it against the new cell's reported capacity. A fresh cell has zero cycle history, so the BIOS flags a mismatch until a learn cycle writes new baseline data. This is a firmware behaviour, not a fault with the replacement cell. Run one complete discharge-to-hibernate then a full uninterrupted charge — the BIOS recalibrates and the health warning clears.

HP laptop shutting down at 20–30% charge shown on screen

The fuel gauge IC calibrates against the old cell's discharge curve. After a swap, it still uses the previous cell's voltage-to-capacity map, so it misreads the remaining charge at load. Under full CPU and display draw, the new cell hits its actual low-voltage threshold before the gauge reaches 0% — and the laptop cuts out. Run two to three full discharge-to-hibernate cycles to let the gauge IC build an accurate curve against the new cell. After calibration, shutdown should not occur above 5–8% reported charge.