About this replacement
Lenovo IdeaPad 1 15IJL7 / 15ALC7 / 15IGL7 Series — 11.25V Li-Polymer Replacement Battery (L21M3PF0)
This is an 11.25V, 3600mAh (40.5Wh) lithium-polymer battery for the Lenovo IdeaPad 1 series, including the 15IJL7, 15ALC7, 15IGL7, and 15IAU7 among 163+ confirmed variants. It replaces OEM parts L21C3PF0, L21D3PF0, L21M3PF0, L21M3PF1, 5B11D70891, and related part numbers. Install when the original cell no longer holds charge, shuts down unexpectedly, or fails to register in the OS.
- IdeaPad 1 multi-variant compatibility: The 15IJL7, 15ALC7, 15IGL7, and 15IAU7 share the same battery bay dimensions, connector pinout, and BMS handshake protocol. Lenovo used the same L21-series cell spec across these platforms, which is why a single part number covers all of them.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an IdeaPad 1 platform. The BMS communicated correctly with the EC, reported accurate state-of-charge to the OS, and held voltage within spec through load transitions from idle to full CPU and display draw.
- BIOS learn cycle after install: After fitting this battery, 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 after every cell swap on IdeaPad 1 hardware.
Laptop shuts down at 20–30% after battery swap
This happens because the fuel gauge IC still holds calibration data from the old cell. Under combined CPU and display load, the new cell's actual voltage curve doesn't match the stored profile, so the EC triggers a low-voltage shutdown earlier than the displayed percentage suggests. The fix is a full calibration cycle: discharge to hibernate, then charge to 100% without interruption. After two or three full cycles, the fuel gauge IC recalibrates against the new cell and the early shutdowns stop.
BIOS reporting battery Wh as incorrect after fitting a new cell
The Wh value shown in BIOS and Lenovo Vantage comes from EEPROM data written at the factory — it reflects the original cell's rated spec, not a live measurement. A new cell with matching chemistry but a slightly different EEPROM write will sometimes display a different Wh figure. This is not a fault with the replacement cell. Confirm the physical specs match the product data — 11.25V, 40.5Wh — and proceed with the learn cycle to let the EC re-establish accurate readings.