Clevo MobiNote M660 Replacement Battery 11.1V 4400mAh

Clevo MobiNote M660 Series — 11.1V Li-ion Replacement Battery

This 11.1V, 4400mAh (48.84Wh) lithium-ion battery replaces the original cell in the Clevo MobiNote M660, M661, M665, and M660JE notebooks. It fits the full M660 series that shares this battery bay format and connector pinout. Install it when the original cell no longer holds a usable charge or fails to power the system at all.

• M660 series compatibility: The M660, M661, M665, and M660JE share the same battery bay dimensions, connector layout, and BMS communication protocol. One cell fits all four without modification or adapter.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on M660-class hardware. The BMS handshake completed correctly, charge accepted cleanly to 4.2V per cell, and the protection circuit tripped normally at the low-voltage cutoff threshold.
• Post-install calibration on the M660: After fitting this cell, run the notebook down to automatic hibernate, then charge uninterrupted to 100% before resuming normal use. This forces the BIOS to complete its battery learn cycle against the new cell and clears the inaccurate health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after fitting the new cell

The M660 BIOS reads health data stored in the cell's EEPROM. When a new cell arrives, that EEPROM holds factory default values that do not match the BIOS's learned parameters from the old battery. The firmware flags this mismatch as degraded health rather than recognising it as a new cell. One full discharge-to-hibernate followed by an uninterrupted charge to 100% lets the BIOS rewrite its learned data against the new cell and clear the warning.

Notebook shuts down abruptly at 20–30% charge shown on screen

This happens when the cell voltage drops below the BMS cutoff threshold under combined CPU and display load, even though the fuel gauge still reads 20–30%. The fuel gauge IC calibrates against the old cell's discharge curve, so its percentage estimate becomes inaccurate with a new cell. The BMS cuts power at the actual low-voltage threshold — around 9V pack voltage — regardless of what the gauge displays. Two to three full calibration cycles bring the fuel gauge IC back into alignment with the new cell's actual discharge curve.