About this replacement
Lenovo ThinkPad X390 Yoga — 11.52V Li-Polymer Replacement Battery (02DL021)
This is an 11.52V, 4100mAh (47.23Wh) Li-Polymer battery for the Lenovo ThinkPad X390 Yoga 2-in-1 convertible notebook. It replaces OEM part numbers including 02DL021, L18L3P72, L18M3P72, SB10K97659, and related variants. It fits X390 Yoga units across the 05CD, 08CD, and 20NNA007CD build codes.
- X390 Yoga platform compatibility: All ThinkPad X390 Yoga variants share the same 11.52V three-cell Li-Polymer architecture, connector pinout, and BMS handshake protocol. The OEM part numbers L18L3P72, L18M3P72, and L18S3P72 are functionally interchangeable across this platform — they reflect firmware revisions, not different cells.
- Bench tested on actual hardware: We ran this cell on a ThinkPad X390 Yoga under mixed CPU and display load. The BMS communicated correctly over SMBus, charge current stepped down properly at the 80% threshold, and cell voltage held within spec under sustained load without triggering a protective cutoff.
- First-cycle reset after install: After fitting this battery, discharge the laptop to hibernate cutoff — not just sleep — then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to recalibrate against the new cell and clears the inaccurate health warning that appears after every cell swap on ThinkPad firmware.
BIOS reporting battery health as poor immediately after replacement
The ThinkPad BIOS reads health data from EEPROM embedded in the battery pack. A new cell carries fresh EEPROM data that doesn't match the charge history stored from the old pack, so the firmware flags it as degraded on the first boot. This is a firmware calibration issue, not a cell defect. Run one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100% — the BIOS battery learn cycle will rewrite its baseline and the poor health warning will clear.
Laptop shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC hasn't yet calibrated against the new cell's actual voltage curve. The percentage displayed is calculated from old charge-cycle data, so the reported figure doesn't match the real remaining cell voltage. Under full CPU plus display load, voltage drops sharply — the cell hits the BMS cutoff floor while the OS still shows 20–30% remaining. Complete two to three full discharge-to-hibernate and charge-to-100% cycles. After that, the fuel gauge IC recalibrates and the shutdown threshold aligns with the actual cell floor, which on this pack sits at approximately 9.0V.