NoteBook Co. 6400AT Replacement Battery 10.8V 6600mAh

NoteBook Co. 6400AT — 10.8V Li-ion Replacement Battery (DR202)

This is a 10.8V, 6600mAh lithium-ion replacement battery for the NoteBook Co. 6400AT laptop. It also cross-references OEM part numbers EMC36, ME202BB, NL2020, and SMP02. Voltage and capacity match the original cell spec exactly.

• 6400AT platform fitment: The 6400AT uses a three-cell series configuration across two parallel strings, locking it to a 10.8V nominal rail. Any replacement must match that rail and present the correct BMS handshake data over the SMBus line — otherwise the laptop refuses to charge the cell.
• Bench tested on actual hardware: We cycled this cell through full charge and controlled discharge on the 6400AT platform. The BMS negotiated correctly at first contact, charge current tapered as expected near full capacity, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
• First-cycle calibration on the 6400AT: After installation, run one full discharge until the laptop hibernates, then charge uninterrupted to 100% without interruption. This forces the BIOS battery learn cycle to reset against the new cell's actual capacity and clears the inaccurate health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after swap

The 6400AT reads battery health data from EEPROM registers stored on the original cell's BMS chip. When a new cell is installed, those registers carry default or mismatched values that the BIOS flags as degraded. This is a data mismatch, not a cell fault. Running one full discharge-to-hibernate followed by an uninterrupted charge to 100% triggers the BIOS learn cycle, which overwrites the stale EEPROM values. After two to three cycles, the health readout normalises.

Laptop shuts down suddenly with 20–30% charge still showing on screen

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The gauge was mapped to the old, degraded cell and underestimates how quickly voltage drops under combined CPU and display load. When real cell voltage hits the hardware cutoff threshold — typically around 9.0V for a 10.8V Li-ion pack — the laptop cuts power regardless of what the OS gauge displays. Run two full discharge-to-hibernate and uninterrupted recharge cycles to let the fuel gauge IC relearn the curve against the new cell.