About this replacement
Lenovo IdeaPad S21E-20 — 7.4V Li-Polymer Replacement Battery (L14M4P22)
This is a 7.4V, 3100mAh (22.94Wh) Li-Polymer battery for the Lenovo IdeaPad S21E-20 and IdeaPad S21E-20 80M4 notebooks. It replaces OEM part numbers L14M4P22 and 5B10H13100. Install it when the original cell no longer holds charge or the system reports degraded battery health.
- IdeaPad S21E-20 and 80M4 compatibility: Both variants run the same 7.4V two-cell Li-Polymer architecture, use the same connector pinout, and communicate with the same BMS handshake over the SMBus line — so one cell fits both board revisions without modification.
- Bench tested on actual hardware: We seated this cell in an IdeaPad S21E-20, confirmed charge acceptance from 0% to 100%, and verified the BMS reported no fault codes across a full discharge cycle under CPU and display load.
- Post-install learn cycle for the S21E-20: After fitting this cell, run the laptop down to hibernate cutoff on battery power, then charge uninterrupted to 100% without waking it mid-cycle. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this model.
BIOS reporting poor battery health immediately after fitting a new cell
The IdeaPad S21E-20 stores cycle count, full-charge capacity, and health status in EEPROM on the battery controller. When you swap the physical cell, the BIOS reads stale EEPROM data from the old battery's last known state and flags it as degraded. This is a data mismatch, not a fault with the replacement cell. Run one complete discharge-to-hibernate then a full uninterrupted charge to 100% — the BIOS battery learn cycle overwrites the stale EEPROM values and the health warning clears.
Laptop shuts down at 20–30% remaining shown on the fuel gauge
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual discharge curve. The old curve mapped a voltage cliff at a higher state-of-charge than where the new cell actually drops off under full CPU plus display load. The system cuts power because the real terminal voltage hits the low-voltage threshold before the gauge expects it. Run two to three full discharge-and-charge cycles and the fuel gauge IC recalibrates — after that, the shutdown point tracks accurately to the cell's true voltage floor near 6.0V.