Lenovo ThinkPad 13 Chromebook SB10J78997 Compatible Battery 11.4V 3600mAh

Lenovo ThinkPad 13 Chromebook — 11.4V Li-Polymer Replacement Battery (SB10J78997)

This 11.4V, 3600mAh (41.04Wh) lithium-polymer cell replaces the original battery in the Lenovo ThinkPad 13 Chromebook and ThinkPad 13 series notebooks. It fits models including the 20GL0000US and the ThinkPad S2 2018 (20L1A001CD), matching the OEM connector and BMS handshake. Install it when the original cell no longer holds a charge or the system reports degraded battery health.

• ThinkPad 13 and S2 2018 platform fit: These models share the same 11.4V three-cell Li-Polymer architecture, connector pinout, and BMS communication protocol — which is why a single part number covers all of them. The battery management system on each variant expects the same voltage rails and cell authentication data.
• Bench tested on actual hardware: We cycled this cell on a ThinkPad 13 Chromebook unit and confirmed the BMS accepted the new cell without triggering a fault flag. Charge termination fired correctly at full capacity and the protection circuit responded to load spikes during display and CPU stress without tripping the safety cutoff.
• Post-swap learn cycle on ThinkPad firmware: After fitting this cell, run one full discharge to the 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 ThinkPad hardware.

Why the ThinkPad 13 shuts down at 20–30% after a battery swap

The fuel gauge IC on the ThinkPad 13 mainboard stores discharge curve data from the old cell. When a new cell goes in, that stored curve no longer matches the actual chemistry, so the gauge misreads remaining capacity. Under combined CPU and display load, the cell voltage drops faster than the gauge expects — the system hits the hardware low-voltage cutoff before the OS gauge reaches 0%. Running two full discharge-to-hibernate and charge-to-100% cycles recalibrates the gauge against the new cell's actual curve.

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

ThinkPad firmware reads health data from the EEPROM embedded in the battery's BMS — not from live cell measurements. A freshly installed cell arrives with EEPROM values that don't match the discharge history the BIOS expects, so it flags the battery as degraded or unknown. This is a data mismatch, not a fault with the cell itself. Complete one full learn cycle — discharge to hibernate cutoff, then a full uninterrupted charge to 100% — and the BIOS health indicator will update to reflect the actual cell condition.