About this replacement
Acer Aspire S7 11" — 7.4V Li-Polymer Replacement Battery (AP12E3K)
This 7.4V, 3790mAh Li-Polymer battery replaces the AP12E3K cell in the Acer Aspire S7 11" ultrabook. It fits the S7-191 and S7 Ultrabook IPS variants — the slim 11-inch models that use a flat polymer pack seated beneath the chassis. Voltage and capacity match OEM spec exactly.
- S7-191 platform fit: All S7 11" variants listed here share the same voltage rail, flat polymer form factor, and AP12E3K connector pinout. The BMS handshake runs on the same SMBus line across the range, so one cell covers the full group.
- Bench tested on actual hardware: We cycled this cell on an S7-191 chassis, confirmed the BMS accepted the pack without fault codes, and verified the charge circuit handed off cleanly at 8.4V full-charge cutoff.
- Post-install calibration on the S7: After fitting, run the laptop on battery until Windows forces hibernate — do not interrupt. Then charge uninterrupted to 100%. This single discharge-charge cycle resets the BIOS battery learn cycle and clears the inaccurate health warning the S7 throws after any cell swap.
Why the S7 BIOS reports poor battery health immediately after a cell swap
The Aspire S7 stores charge history and health data in EEPROM on the battery's BMS board. When a new cell is installed, the BIOS reads stale EEPROM data — either from a partially written previous pack or from default factory values it doesn't recognise. This triggers a "battery health poor" or "replace battery" flag in the BIOS and Acer Power Management. It is not a fault with the replacement cell. One full discharge-to-hibernate followed by an uninterrupted charge to 100% gives the BIOS enough cycle data to overwrite the flag.
S7 shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC hasn't yet mapped the new cell's discharge curve. The IC was calibrated against the old, degraded cell — so it misjudges where the voltage cliff sits on the fresh pack. Under combined CPU and display load, the real cell voltage drops faster than the gauge predicts, and the system cuts out before the displayed percentage reaches zero. Run two full discharge-to-hibernate cycles and charge completely each time. After those calibration passes, the gauge IC aligns to the new cell and the shutdowns stop.