Advent 7109B Laptop Compatible Battery 10.8V 4400mAh

Advent 7109B / 8117 Series — 10.8V Li-ion Replacement Battery (L50-3S4400-S1S5)

This is a 10.8V, 4400mAh Li-ion battery for the Advent 7109B, 7109A, 8117, and 7113 notebooks. It replaces a long list of OEM part numbers across the L50 and L51 series. Capacity is 47.52Wh — matched to the original specification.

• L50 and L51 series compatibility: These models share the same voltage rail, battery bay dimensions, and connector pinout. The BMS handshake uses the same communication protocol across the L50 and L51 variants, so one cell covers all listed models without adapter or modification.
• Bench tested on actual hardware: We cycled this cell through charge, full discharge to protection cutoff, and back to 100%. The BMS responded correctly at both ends — no false low-voltage trips and no charge interruption before capacity was reached.
• Post-install calibration on the 7109B: After fitting, run one full discharge until the laptop hibernates on its own, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that typically appears after a cell swap on this platform.

BIOS reporting poor battery health immediately after replacement

The BIOS on the Advent L50/L51 platform reads health data stored in the old cell's EEPROM. When a new cell goes in, that data is gone — the BIOS flags it as degraded or unknown before any charge history exists. This is not a fault with the replacement cell. Run one full discharge-to-hibernate cycle, then a full uninterrupted charge. After two to three cycles, the fuel gauge IC recalibrates against the new cell's actual capacity and the health warning clears.

Laptop shuts down at 20–30% charge remaining

This happens when the cell voltage drops sharply under combined CPU and display load — a voltage cliff the fuel gauge misreads as 20–30% remaining. The OS is reading an uncalibrated fuel gauge IC that still references the old cell's discharge curve. The fix is a calibration cycle: discharge fully to hibernate cutoff, then charge to 100% without interrupting. Repeat twice. If the shutdowns continue past three calibration cycles, check that the BIOS is not running a conservative charge limit — enter BIOS setup and confirm no power-management charge cap is active.