M540BAT-6 Clevo MobiNote M54 Replacement Battery 11.1V 4000mAh

Clevo MobiNote M54 / M55 Series — 11.1V Li-ion Replacement Battery (M540BAT-6)

This is an 11.1V, 4000mAh (44.4Wh) Li-ion battery for the Clevo MobiNote M54, M55, M540, and M541 series laptops. It replaces OEM part numbers M540BAT-6, BAT-5420-A, BAT-5422, BAT-5560-A, and BAT-5522, among others. The cell fits the same bay and uses the same connector and BMS handshake as the original Clevo unit.

• M54 / M55 / M540 / M541 platform fit: These models share a common battery bay dimension, pin-out, and BMS communication protocol across the MobiNote line. One cell revision covers the full spread of OEM part numbers listed above without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a MobiNote M54 chassis. The BMS negotiated charge termination correctly at 12.6V, and the protection circuit tripped as expected on simulated cell stress — no thermal runaway, no false cutoff at mid-charge.
• First-cycle calibration on the MobiNote: After fitting, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.

Why the MobiNote M54 shuts down at 20–30% remaining after a battery swap

The M54's fuel gauge IC built up a charge map against the old degraded cell over months of use. When a fresh cell goes in, that map is wrong — the IC thinks the voltage cliff starts earlier than it does. Under full CPU plus display load, the laptop sees a voltage reading that matches its learned low-battery threshold and cuts power before the cell is truly empty. Running two to three full discharge-to-hibernate cycles forces the fuel gauge IC to rebuild its map against the new cell's actual discharge curve. After calibration, the reported percentage tracks accurately down to the real low-voltage cutoff.

BIOS reporting battery health as "poor" or "unknown" immediately after fitting

The BIOS reads health status from EEPROM data stored in the battery's BMS — the new cell ships with default factory values, not data matched to the M54's charge history. Until the learn cycle runs, the BIOS compares those defaults against its own records and flags a mismatch as poor health or unknown. This is not a fault with the cell. Charge to 100%, discharge fully to hibernate, then charge again uninterrupted — the BIOS re-reads the EEPROM after each completed cycle and updates the health status accordingly. After two cycles the warning clears on most M54 BIOS revisions.