About this replacement
Lenovo ThinkPad P1 / X1 Extreme — 15.36V Li-Polymer Replacement Battery (L17M4P72)
This is a 15.36V 5150mAh (79.1Wh) Li-Polymer replacement battery for the Lenovo ThinkPad P1 and X1 Extreme series. It fits models including the ThinkPad P1 (20MD000DGE), ThinkPad X1 Extreme-20MF000XGE, and ThinkPad X1 YINSHI 20MFA002CD, among others. Cross-references include OEM part numbers L17C4P72, L17L4P72, SB10Q76928, and 01AY968.
- ThinkPad P1 and X1 Extreme platform fit: These models share the same 15.36V four-cell battery bay, connector pinout, and BMS handshake protocol — one cell covers all listed variants without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a ThinkPad P1 unit. The BMS communicated correctly with the BIOS, voltage held stable under sustained CPU and display load, and charge termination triggered cleanly at capacity.
- Post-swap BIOS learn cycle: After installing, run one full discharge to 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 replacement on this platform.
Why the ThinkPad P1 shuts down at 20–30% after a battery swap
The ThinkPad P1 runs a quad-core workstation CPU alongside a dedicated NVIDIA Quadro GPU. Under full load, instantaneous current draw spikes hard. If the fuel gauge IC has not yet calibrated against the new cell, it misreads the remaining capacity — the BIOS sees a voltage cliff and triggers an emergency shutdown at what looks like 25% on screen. The fix is two to three full discharge-to-hibernate and uninterrupted-charge cycles. After calibration, the gauge tracks the new cell accurately and the premature shutdowns stop.
BIOS reporting wrong Wh rating after cell replacement
When you swap the battery, the BIOS reads Wh data from the cell's EEPROM, not from live measurement. The stored EEPROM value on replacement cells can differ slightly from the rated 79.1Wh shown in system info. This is a data field mismatch, not a capacity fault. To confirm actual capacity, run a full discharge cycle and check the reported full-charge capacity in Lenovo Vantage or a battery diagnostic tool — it should settle close to 79.1Wh after two calibration cycles.