About this replacement
Lenovo ThinkPad X1 Nano Gen 2 — 11.61V Li-Polymer Replacement Battery (L21C3P74)
This is an 11.61V, 4150mAh (48.18Wh) Li-Polymer battery for the Lenovo ThinkPad X1 Nano Gen 2. It fits the 21E8001KEE, 21E8001QRI, 21E80024UE, 21E80005EQ, and over 120 additional X1 Nano Gen 2 configurations. It replaces OEM part numbers L21C3P74, L21D3P74, L21L3P74, L21M3P74, 5B11F28680, 5B11F28682, SB11B44632, SB11F28677, and SB11F28679.
- X1 Nano Gen 2 platform fit: All listed Gen 2 variants share the same 11.61V three-cell Li-Polymer architecture, connector pinout, and BMS handshake protocol. One cell covers every SKU in that generation without any modification.
- Bench tested on actual hardware: We cycled this cell through charge, discharge, and system wake events on the X1 Nano Gen 2 platform. The BMS communicated correctly with the EC firmware, and the charge controller accepted the cell without fault codes.
- Post-install calibration on the X1 Nano Gen 2: After fitting the new cell, run one full discharge until the laptop hibernates, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.
BIOS reporting battery health as poor after replacement on the X1 Nano Gen 2
The X1 Nano Gen 2 stores battery health data in the embedded controller's EEPROM, which retains metrics from the old cell after a swap. When the new cell's EEPROM data doesn't match the EC's learned values, ThinkPad BIOS flags the battery as degraded or unknown — even on a brand-new cell. This is a calibration state, not a hardware fault. Run the BIOS battery gauge reset under Power Manager or complete one full discharge-to-hibernate followed by an uninterrupted full charge to re-anchor the health baseline.
ThinkPad X1 Nano Gen 2 shutting down at 20–30% charge shown
This happens when the fuel gauge IC hasn't yet mapped the new cell's actual voltage-to-capacity curve. The EC predicts remaining charge based on the old cell's profile and miscalculates the voltage cliff point, cutting power before the display shows zero. It's not a faulty cell — it corrects after two to three full calibration cycles. Discharge to hibernate, charge fully to 100%, and repeat twice; the OS percentage and actual cutoff voltage will align by the third cycle.