IBM ThinkPad 380 10.8V Replacement Battery 02K6417 4400mAh

IBM ThinkPad 380 Series — 10.8V Li-ion Replacement Battery (02K6417)

This 10.8V, 4400mAh Li-ion battery replaces the original cell in the IBM ThinkPad 380 and its variants — 380CE, 380CS, and 380CSE among others. It matches the OEM voltage rail and connector footprint for the 380 series. Cross-reference your original part against 02K6417, 02K6503, 02K6507, 02K6509, 02K6516, or 02K6517 before ordering.

• ThinkPad 380 series fit: The 380, 380CE, 380CS, and 380CSE all share the same battery bay dimensions, 10.8V nominal voltage rail, and connector pinout — which is why one cell covers the full sub-series without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on ThinkPad 380 hardware. The BMS handshake completed without error flags, and the cell accepted a full charge to 47.52Wh capacity with no thermal events.
• First-cycle calibration after install: After fitting this battery, run the laptop on battery power until it hibernates at low-voltage 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 the 380 series.

ThinkPad 380 shutting down at 20–30% charge shown on screen

This is a voltage cliff, not a fuel gauge error. Under combined CPU and display load, cell voltage drops faster than the fuel gauge IC can track — the laptop sees the voltage fall below the BMS cutoff threshold while the OS still reports 20–30% remaining. It happens most often on a freshly installed cell that has not yet been calibrated. Run one full discharge to hibernate, then a full uninterrupted charge to 100%. After two to three calibration cycles, the gauge IC aligns to the new cell's actual discharge curve and the premature shutdowns stop.

BIOS reporting new battery health as poor immediately after swap

The ThinkPad 380 BIOS reads health data from EEPROM registers written by the previous cell. When a new cell arrives, those registers either hold stale degraded-cell data or are blank — both read as poor health in the BIOS summary screen. This is a data state issue, not a fault with the replacement cell. Run the battery learn cycle: discharge fully to hibernate cutoff, charge to 100% without interruption, and repeat once more. After two full cycles the BIOS rewrites the EEPROM health registers against the new cell's actual charge capacity and the poor-health flag clears.