About this replacement
NEC Lavie PC-LL7509D Series — 14.8V Li-Polymer Replacement Battery (APA000084900)
This 14.8V, 4400mAh lithium-polymer battery replaces the original cell in the NEC Lavie PC-LL7509D and related models including the PC-LL750AD, PC-LL7709DT, and PC-LL770AD. It matches the OEM voltage rail and connector pinout for direct installation. Capacity is 65.12Wh, identical to the original specification.
- Lavie series compatibility: These Lavie notebooks share the same 14.8V four-cell Li-Polymer architecture, connector housing, and BMS communication protocol — which is why one cell covers the full model range listed above.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on the Lavie platform. The BMS handshake completed correctly, charge termination triggered at 16.8V, and the protection circuit tripped as expected at the low-voltage cutoff threshold.
- Post-installation calibration — Lavie BIOS battery learn cycle: After fitting this cell, run one full discharge until the laptop hibernates, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on Lavie hardware.
BIOS reporting poor battery health immediately after fitting the new cell
The Lavie BIOS reads health data stored in the old cell's EEPROM and compares it against the new cell's reported values. When a fresh cell is installed, the EEPROM data does not match the learned cycle history, so the BIOS flags it as degraded. This is not a fault with the replacement cell — it is a firmware artefact. Run one full discharge-to-hibernate followed by an uninterrupted full charge. After two to three cycles the BIOS recalculates health from live data and the warning clears.
Laptop shuts down at 20–30% charge shown on the fuel gauge
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The IC inherited capacity data from the old, degraded cell and cuts system power when voltage drops below its learned threshold — even though the new cell still has usable charge remaining. Complete two full discharge-to-hibernate cycles followed by full uninterrupted charges. After calibration, the fuel gauge tracks the new cell accurately and the early shutdowns stop. If the issue persists beyond three cycles, check that the cell resting voltage reads above 14.4V before boot.