About this replacement
Lenovo Legion Y740 / Y730 Series — 15.36V Li-Polymer Replacement Battery (L17M4PG2)
This 15.36V, 4800mAh (73.73Wh) Li-Polymer battery replaces the original cell in the Lenovo Legion Y740 and Y730 17-inch gaming laptops. It covers OEM part numbers including L17M4PG2, L17C4PG2, L17L4PG2, L17S4PG2, and 5B10Q88556, among others. Confirmed fit includes the Y740-17ICHg, Y740-17IRHg, and Y730-17ICH series.
- Legion Y740 / Y730 17-inch platform: These models share a 15.36V four-cell Li-Polymer architecture with a common BMS handshake protocol. The connector pinout and communication lines are identical across the Y730 and Y740 17-inch variants, which is why one cell covers all of them.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a Y740-17 unit. The BMS negotiated correctly, charge current stepped down cleanly at 95%, and the fuel gauge IC accepted the new cell data without flagging an error state.
- Post-swap BIOS recalibration: After installation, run one 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 after swapping a new cell into this platform.
Laptop shutting down at 20–30% shown after battery swap
This happens because the Legion Y740 runs a combined CPU and discrete GPU load that draws heavy current bursts during gameplay or rendering. Under that load, a partially calibrated cell hits a voltage cliff earlier than the fuel gauge predicts, and the BIOS triggers an emergency shutdown. The fuel gauge IC is reading state-of-charge from a model built on the old cell's discharge curve. Run two complete discharge-to-hibernate and full-charge cycles — this forces the gauge IC to rebuild its curve against the new cell, and the premature shutdowns stop.
BIOS reporting battery Wh rating as wrong after installation
The Wh value shown in Lenovo Vantage or Windows power settings reads from EEPROM data embedded in the BMS, not from the physical cell. When a replacement cell carries EEPROM values from a slightly different production batch, the reported Wh figure may not match the label. This is a data field mismatch — it does not affect charging behaviour or actual capacity delivered. Check the actual charge held via a full cycle; if the laptop runs as expected, the discrepancy is cosmetic only.