About this replacement
Lenovo IdeaPad Y900 / Y910 Series — 11.1V Li-ion Replacement Battery (L14M6P21)
This is an 11.1V, 8100mAh (89.91Wh) Li-ion battery pack for the Lenovo IdeaPad Y900 and Y910 gaming notebooks. It replaces OEM part numbers L14M6P21, 5B10H35531, 5B10H35530, 5B10N00788, and 5B10N00789. It fits the Y900-17ISK and Y910 variants listed under Lenovo's 80Q1 chassis family.
- Y900 and Y910 chassis compatibility: Both models share the same 11.1V battery rail, connector pinout, and BMS handshake protocol. A single cell fits the full platform without hardware modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Y900-17ISK unit. The BMS negotiated correctly with the Lenovo EC firmware, and charge termination triggered cleanly at full capacity without cutoff errors.
- Post-install calibration on the Y900: After fitting this cell, run a full discharge until the laptop hibernates, then charge uninterrupted to 100% without interruption. This resets the BIOS battery learn cycle and clears the inaccurate health warning the Y900's EC logs after every cell replacement.
Why the IdeaPad Y900 shuts down at 20–30% after a battery swap
The Y900's fuel gauge IC stores learned discharge curves from the previous cell in EEPROM. When a new cell goes in, those stored curves no longer match the actual chemistry, so the gauge reads voltage collapse earlier than it occurs. The laptop interprets this as a critical low-power state and triggers shutdown — even though the new cell still holds usable charge. Running two full discharge-to-hibernate and full-charge cycles forces the fuel gauge IC to rebuild its model against the new cell's actual voltage curve. After calibration, the reported percentage and the real state of charge align correctly.
BIOS showing "Battery health: poor" or "Unknown" on a new cell
Lenovo's BIOS reads health data from the battery's EEPROM — specifically the cycle count and rated Wh values written at the cell level. An aftermarket cell ships with EEPROM values that differ from the original OEM record, and the BIOS flags this as degraded or unrecognised. This is a data mismatch, not a fault with the cell itself. Run the battery learn cycle via Lenovo Vantage — navigate to Device → Power → Battery Settings and run the "Battery Gauge Reset" — this re-initialises the BIOS health register against the installed cell at 11.1V nominal.