About this replacement
Lenovo ThinkBook 14 G4 IAP — 15.52V Li-Polymer Replacement Battery (L21C4PD6)
This is a 15.52V, 3850mAh (59.75Wh) Li-Polymer battery for the Lenovo ThinkBook 14 G4 IAP series. It fits models including the 21CX000HRE, 21CX001NRM, 21CX004DAK, and 21CX000EAT among 136+ variants. It replaces OEM part numbers L21C4PD6, L21D4PD6, L21L4PD6, L21M4PD6, and SB11E40205.
- ThinkBook 14 G4 IAP compatibility: All 21CX-series variants share the same 15.52V four-cell Li-Polymer architecture, connector pinout, and BMS handshake protocol. That consistent platform spec is why a single cell replacement covers the full production run of this generation.
- Bench tested on actual hardware: We ran this cell on a ThinkBook 14 G4 IAP chassis. The BMS initialised cleanly, charge accepted across all four cells without balancing errors, and the pack reached full voltage without triggering a protection cutoff.
- Post-install discharge cycle on ThinkBook 14 G4 IAP: After fitting this cell, 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 in Lenovo Vantage after every cell swap.
BIOS reporting poor battery health immediately after replacement
The ThinkBook 14 G4 IAP stores battery health data in EEPROM on the original cell. When a new cell goes in, the BIOS reads a blank or mismatched EEPROM and flags the battery as degraded or unknown. This is not a fault with the replacement cell — it is stale data from the previous pack. Running the Lenovo battery learn cycle through Lenovo Vantage, or completing one full discharge-to-hibernate then a full uninterrupted charge, allows the firmware to rewrite that EEPROM data against the new cell's actual capacity curve.
Laptop shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC has not yet calibrated to the new cell's voltage-to-capacity curve. The gauge predicts remaining charge based on the old cell's profile, so it under-reports how far down the voltage has actually dropped. Under combined CPU and display load, the cell hits its real low-voltage cutoff before the OS gauge reaches 0%. Complete two full discharge-to-hibernate cycles followed by uninterrupted charges to 100%. After those calibration passes, the fuel gauge tracks actual cell voltage accurately and the early shutdowns stop.