About this replacement
Lenovo ThinkBook Plus G3 IAP — 15.44V Li-Polymer Replacement Battery (5B11H10608)
This 15.44V, 4350mAh (67.16Wh) Li-Polymer cell replaces OEM part numbers 5B11H10608, L21C4PH4, L21D4PH4, L21L4PH4, and L21M4PH4. It fits the ThinkBook Plus G3 IAP series — a 14-inch dual-screen business notebook with an integrated e-ink display. If the original cell has degraded or failed entirely, this restores full charging capability to the system.
- ThinkBook Plus G3 IAP series fit: All ThinkBook Plus G3 IAP variants share the same 15.44V four-cell battery rail, identical connector pinout, and compatible BMS handshake — which is why a single part number covers the full model range across regional SKUs.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the ThinkBook Plus G3 IAP platform. The BMS communicated correctly with the BIOS throughout, with no charge interruption, no false thermal cutoff, and steady voltage delivery across both the main display and the e-ink panel simultaneously.
- Post-swap calibration on the ThinkBook Plus G3 IAP: After installing, run one full discharge down 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 battery health as poor immediately after replacement
The ThinkBook Plus G3 IAP BIOS reads battery health data stored in the old cell's EEPROM and compares it against the new cell on first boot. Because the new cell has no accumulated cycle data, the BIOS flags it as unrecognised or degraded — not a fault with the replacement. Running a full discharge-to-hibernate followed by an uninterrupted charge to 100% forces the BIOS to complete a battery learn cycle and write fresh EEPROM data. After one or two full cycles, Lenovo Vantage and the BIOS will report health accurately. No firmware update is needed.
Laptop shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC on the motherboard is still calibrated to the old, degraded cell. The IC predicts voltage behaviour based on the previous cell's profile, so when the new cell hits its actual load voltage under combined CPU and e-ink panel draw, the reading drops faster than the IC expects — triggering an early shutdown. It is not a defect in the new cell. Perform a full calibration cycle: discharge to automatic hibernate, then charge to 100% without interruption. After two to three full cycles, the fuel gauge recalibrates to the new cell and cutoff returns to the correct voltage floor near 12.8V.