About this replacement
Lenovo Legion 7 16IAX7 — 15.44V Li-Polymer Replacement Battery (L21C4PC2)
This is a 15.44V, 5050mAh (77.97Wh) Li-Polymer battery for the Lenovo Legion 7 16IAX7 series gaming laptop. It replaces OEM part numbers L21C4PC2, L21L4PC2, and L21M4PC2. The battery fits the 82TD chassis line, covering over 150 regional variants of the 16-inch Legion 7.
- Legion 7 16IAX7 82TD chassis compatibility: All variants in this chassis share the same 15.44V four-cell configuration, connector pinout, and BMS handshake protocol. The L21-series part number spans regional SKUs — the underlying cell pack and communication interface are identical across them.
- Bench tested on actual hardware: We cycled this cell on a Legion 7 16IAX7 unit under combined CPU and display load. The BMS held the charge curve without triggering overcurrent cutoff, and the fuel gauge IC tracked state-of-charge accurately after two calibration cycles.
- BIOS learn cycle after install: After fitting this battery, run a 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 swap on Legion hardware.
BIOS reporting poor battery health immediately after replacement
The Legion 7 BIOS reads health data from EEPROM stored on the old cell. When a new cell is installed, that EEPROM data is gone and the BIOS flags the battery as degraded or unknown until it completes a learn cycle. This is a firmware state issue, not a fault with the replacement cell. Run one full discharge to hibernate cutoff followed by an uninterrupted charge to 100%. After that cycle, the BIOS recalibrates against the new cell's actual capacity curve.
Laptop shutting down with 20–30% charge still showing on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's voltage-to-capacity curve. Under full CPU plus display load, the cell voltage drops faster than the gauge predicts, and the system hits the low-voltage cutoff before the displayed percentage reaches zero. It is not a defective cell — the gauge is reading stale data mapped to the old cell. Complete two full discharge-to-hibernate and charge-to-100% cycles. After that, the fuel gauge IC locks onto the correct voltage curve and the shutdowns stop.