About this replacement
Lenovo ThinkBook 14 G4+IAP — 11.52V Li-Polymer Replacement Battery (L21M3PD7)
This is an 11.52V, 4850mAh (55.87Wh) Li-Polymer replacement battery for the Lenovo ThinkBook 14 G4+IAP and ThinkBook 16 G4+ ARA. It replaces OEM parts L21M3PD7, L21C3PD7, L21D3PD7, L21L3PD7, 5B10Z21201, and SB10Z21205. Fits the 21CY0037SA configuration as well.
- ThinkBook G4+ platform compatibility: The ThinkBook 14 G4+IAP and 16 G4+ ARA share the same 11.52V three-cell Li-Polymer architecture and BMS handshake protocol. Any battery in this cross-reference group connects through the same five-pin connector and communicates on the same SMBus line, which is why a single cell covers both chassis.
- Bench tested on actual hardware: We cycled this cell on a ThinkBook 14 G4+IAP unit and confirmed the BMS authenticated correctly, reported accurate state-of-charge, and did not trigger a low-voltage protection cutoff during a full discharge-to-hibernate sequence.
- BIOS learn cycle after installation: After fitting this battery, run one full discharge down to hibernate cutoff, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on ThinkBook G4+ hardware.
BIOS reporting battery health as poor immediately after replacement
The ThinkBook BIOS reads health data from EEPROM registers carried over from the original cell, not from live measurements of the new one. When a new cell is installed, the BIOS compares its historical cycle count and capacity fade data against the fresh cell's readings and flags a mismatch as poor health. This is not a fault with the replacement battery. One full discharge-to-hibernate followed by an uninterrupted charge to 100% triggers the BIOS learn cycle, which rewrites the EEPROM baseline to match the new cell's actual chemistry.
Laptop shuts down unexpectedly at 20–30% charge shown
This happens when the fuel gauge IC's stored discharge curve no longer matches the new cell's actual voltage profile. Under combined CPU and display load, the cell voltage drops faster than the old curve predicts, and the system hits the BMS low-voltage cutoff before the gauge reaches 0%. The fuel gauge IC needs two to three full calibration cycles against the new cell to remap the curve accurately. Run full discharges to hibernate cutoff and full charges to 100% until the gauge stabilises — the shutdowns stop once the cell voltage at cutoff aligns with 11.1V on the BMS threshold.