About this replacement
Acer Extensa 5120 / 5230 Series — 10.8V Li-ion Replacement Battery (TM00741)
This is a 10.8V, 4400mAh (47.52Wh) Li-ion cell pack for the Acer Extensa 5120, 5230, 5230E, 5235, and related models. It replaces OEM parts including TM00741, TM00751, AK.006BT.018, and over a dozen cross-reference part numbers. The connector, BMS pinout, and voltage rail match the original Acer specification for this notebook series.
- Extensa 5120–5235 platform fit: These models share a common battery bay format, 10.8V three-cell-series configuration, and the same BMS communication protocol over the SMBus line. One cell pack covers the full range without adapter or modification.
- Bench tested on actual hardware: We ran this pack on an Extensa 5230 unit. The BMS initialised on first connection, the BIOS detected the pack immediately, and charge current ramped correctly through CC-CV stages to 100% without interruption.
- Post-install calibration on Extensa notebooks: After fitting, run the laptop on battery until it hibernates at cutoff, then charge uninterrupted to 100%. This completes the BIOS battery learn cycle 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
Acer's BIOS reads health data stored in the battery pack's EEPROM. When a new cell arrives, its EEPROM registers no charge history, which the BIOS interprets as a degraded or unknown pack. This is a data state issue, not a hardware fault. Running one full discharge-to-hibernate followed by a full uninterrupted charge lets the BIOS log a complete cycle and rewrite its health estimate. After two to three cycles, the health indicator stabilises.
Laptop shuts down while the OS still shows 25–30% charge remaining
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The IC inherited the old cell's voltage-to-capacity map, so it misreads the remaining charge at high CPU and display load. Under that combined load, voltage drops faster than the stale map predicts, and the BMS cuts power to protect the cells before the OS gauge reaches zero. Run two full discharge-to-hibernate cycles and the fuel gauge IC will recalibrate to the new cell — shutdowns under load should stop once the mapped floor voltage aligns with the actual 10.8V pack minimum of approximately 9.0V.