About this replacement
Lenovo ThinkPad P16s Gen 2 (Intel) — 15.4V Li-Polymer Replacement Battery (L21D4P72)
This is a 15.4V, 3300mAh (50.82Wh) lithium-polymer cell for the Lenovo ThinkPad P16s and P16 Gen 1 and Gen 2 series mobile workstations. It replaces OEM part numbers L21D4P72, L21L4P72, 5B10W51868, 5B10W51870, SB10W51969, and SB10W51971. The cell fits the standard battery bay on both Intel and AMD variants of the P16s Gen 1 and Gen 2 platforms.
- Cross-platform P16s and P16 Gen 1/Gen 2 fit: Lenovo shared this battery form factor, connector pinout, and BMS handshake protocol across both the Intel and AMD P16s Gen 1 and Gen 2 lineups. The voltage rail and physical dimensions — 316.30 × 111.70 × 5.60mm — are identical across these variants, so one cell covers the full model range.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a P16s Gen 2 Intel unit. The BMS completed authentication with the EC firmware, reported correct Wh capacity to the OS, and held voltage stable under sustained CPU and display load without triggering low-voltage cutoff prematurely.
- Post-installation learn cycle on the P16s: After fitting this cell, run one full discharge until the laptop hibernates at its low-battery cutoff, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning the ThinkPad BIOS routinely displays after any cell swap.
BIOS reporting poor battery health immediately after fitting a new P16s cell
The ThinkPad BIOS reads battery health from EEPROM data stored in the old cell's fuel gauge IC. When a new cell is installed, that EEPROM record is gone, and the BIOS flags the battery as degraded because it has no calibration baseline yet. This is not a fault with the replacement cell. Running one complete discharge-to-hibernate followed by a full uninterrupted charge gives the fuel gauge IC enough data to write a new baseline. After one or two cycles, the BIOS health indicator resets to normal.
ThinkPad P16s shutting down at 20–30% charge shown on the fuel gauge
This happens when the cell voltage drops below the EC's cutoff threshold under full CPU plus display load before the reported percentage reaches zero — a voltage cliff caused by a degraded cell that cannot sustain current delivery at high draw. A new cell resolves the shutdown, but the fuel gauge IC still needs calibration against the fresh chemistry to track the percentage accurately. Perform the full discharge-to-hibernate cycle once after installation. On the P16s, target a resting voltage of 16.8V at full charge to confirm the cell is within spec.