Lenovo ThinkBook 13s G2 Replacement Battery 15.44V 3550mAh

Lenovo ThinkBook 13s G2 ITL — 15.44V Li-Polymer Replacement Battery (5B10Z37621)

This is a 15.44V, 3550mAh (54.81Wh) Li-Polymer battery for the Lenovo ThinkBook 13s G2 ITL-20V9000LAU and related ThinkBook 13s/14s G2 variants. It replaces OEM part numbers including L19C4PDD, L19D4PDD, L19M4PDD, SB10Z37616, and SB10Z37619. The original cell in these ultrabooks degrades through normal charge cycling — this replacement restores full portable operation.

• ThinkBook 13s G2 and 14s G2 fitment: These models share a 15.44V four-cell Li-Polymer architecture with the same connector pinout and BMS handshake protocol. The ThinkBook 13s G2 ITL, 13s G2 ARE, and 14s G2 ITL all use this cell — the BMS negotiates charge termination and fuel gauge data across the same SMBUS line on each platform.
• Bench tested on actual hardware: We cycled this battery through full charge and discharge on a ThinkBook 13s G2 platform. The BMS accepted the cell without fault codes, charge termination triggered correctly at 16.8V, and the SMBUS communication returned valid state-of-charge data throughout.
• Post-install calibration on ThinkBook G2 platforms: After fitting this cell, run the laptop down to hibernate cutoff — do not interrupt — 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 ThinkBook G2 firmware.

BIOS reporting battery health as poor immediately after replacement

ThinkBook G2 firmware stores learned capacity data in EEPROM on the old cell. When a new cell is installed, the BIOS reads no matching history and flags health as degraded or unknown — this is a firmware read problem, not a fault with the replacement cell. The BIOS battery learn cycle recalibrates this: discharge to hibernate cutoff, then charge to 100% without interruption. After one or two full cycles, the health status updates and the warning clears. If the BIOS still shows poor health after three cycles, confirm the SMBUS connection at the battery connector is fully seated.

ThinkBook 13s shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC has not yet calibrated against the new cell's voltage curve. Under full CPU and display load, the cell voltage drops faster than the old curve predicts, and the system interprets a safe voltage as critically low — triggering shutdown. The fuel gauge IC needs two to three full discharge-and-charge cycles to map the new cell accurately. Run the laptop under normal workload — not idle — during those calibration cycles so the IC captures the voltage sag under real draw. After calibration, the reported percentage at shutdown should align with actual cell voltage at approximately 14.4V.