About this replacement
Lenovo ThinkBook 13s G4 IAP Series — 15.52V Li-Polymer Replacement Battery (5B11D96862)
This 15.52V, 3500mAh (54.32Wh) lithium-polymer battery replaces the original cell in the Lenovo ThinkBook 13s G4 IAP and ARB series ultrabooks. It covers part numbers 5B11D96862, 5B11D96864, L21B4PD0, L21C4PD0, L21D4PD0, L21L4PD0, L21M4PD0, and several SB11D96xxx variants. Physical dimensions are 251.70 x 102.00 x 4.90mm — verify against your existing cell before installing.
- ThinkBook 13s G4 IAP and ARB compatibility: These models share a common 15.52V four-cell Li-Polymer architecture with the same connector pinout and BMS handshake protocol. The BIOS on both IAP (Intel) and ARB (AMD) variants reads battery data through the same SMBus interface, so one cell covers both platforms without firmware conflict.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a ThinkBook 13s G4 platform. The BMS communicated correctly over SMBus, voltage ramp was stable from 12.0V to 17.0V, and no protection trips were triggered during load transitions between idle and full CPU plus display draw.
- Post-installation learn cycle on ThinkBook 13s G4: After fitting this cell, run one full discharge to hibernate cutoff — do not interrupt it — then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
BIOS reporting poor battery health immediately after replacement on ThinkBook 13s G4
The ThinkBook 13s G4 stores battery health data in EEPROM on the old cell. When a new cell is installed, the BIOS reads stale cycle count and capacity figures from that EEPROM record and flags the battery as degraded before it has run a single cycle. This is a data mismatch — not a fault with the replacement cell. Run the full discharge-to-hibernate then uninterrupted charge sequence once. After that first calibration cycle, the BIOS rewrites its health record against the new cell's actual reported data and the warning clears.
Laptop shutting down at 20–30% remaining after battery swap
The fuel gauge IC on this platform calibrates its capacity map against the old cell's voltage curve. On a new cell, the IC misreads the voltage drop under combined CPU and display load as a near-empty condition and triggers shutdown well above actual depletion. The cell still has charge — the gauge just does not know where the voltage cliff sits yet. Two to three full discharge and charge cycles recalibrate the IC against the new chemistry. After calibration, the shutdown point drops back to the correct low-voltage threshold near 11.5V per cell.