About this replacement
Lenovo IdeaPad S540-15IWL GTX — 11.34V Li-Polymer Replacement Battery (L18L3PF6)
This is an 11.34V, 4500mAh (51.03Wh) Li-Polymer replacement battery for the Lenovo IdeaPad S540-15IWL GTX and IdeaPad S540-15IWL laptops. It replaces OEM part numbers L18L3PF6, SB10W67224, 5B10T26389, and 5B10W67284. If the original cell has degraded or fails to hold charge, this swap restores cordless use.
- IdeaPad S540-15IWL and GTX variant: Both the standard S540-15IWL and the GTX variant share the same battery bay dimensions, connector pinout, and BMS handshake protocol — the GTX label indicates the discrete GPU configuration, not a different battery platform.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the S540 platform. The BMS communicated correctly with the EC firmware, reported capacity data to the OS, and held stable voltage across the full discharge curve without triggering a protection cutoff.
- Post-install learn cycle on S540: After fitting, run the battery down until the laptop hibernates, then charge uninterrupted to 100% without using the machine. This gives the BIOS fuel gauge IC one complete reference cycle against the new cell and clears the inaccurate health warning that appears after every cell swap on IdeaPad firmware.
BIOS reporting poor battery health immediately after replacement
The S540 BIOS reads health data stored in the battery's EEPROM and compares it against accumulated cycle history from the previous cell. A new cell presents fresh EEPROM data with zero cycles, which the firmware initially interprets as a mismatch rather than a clean slate. This triggers the "poor health" or "replace battery" flag in Lenovo Vantage or the BIOS setup screen. One full discharge-to-hibernate followed by an uninterrupted charge to 100% resets the learn cycle — run it twice if the warning persists after the first cycle.
Laptop shuts down at 20–30% charge shown on screen
This happens when the fuel gauge IC's stored discharge curve no longer matches the new cell's actual voltage-versus-capacity profile. The OS believes 25% remains, but the cell voltage has already dropped below the BMS cutoff threshold under the combined load of the CPU, display, and GPU — so the system shuts down without warning. The fix is calibration: let the battery discharge fully to hibernate cutoff, then charge to 100% with the laptop off or in sleep mode. After two or three cycles the fuel gauge recalibrates to the new cell and the shutdown at 20–30% stops.