Lenovo ThinkPad P51S Replacement Battery 11.1V 4400mAh

Lenovo ThinkPad P51S / T470 / T570 — 11.1V Li-ion Replacement Battery (SB10K97581)

This is an 11.1V, 4400mAh (48.84Wh) Li-ion battery for the Lenovo ThinkPad P51S, T470, and T570 series laptops. It replaces OEM part numbers including SB10K97581, SB10K97582, 01AV422, 01AV423, and related variants. These are 15-inch mobile workstation and business laptops that run demanding engineering and productivity workloads away from the desk.

• P51S, T470, and T570 compatibility: All three platforms share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The same 11.1V three-cell architecture and SMBus communication lines run across the entire series, so one cell fits all listed models without modification.
• Bench tested on actual hardware: We ran this cell on a T470 and P51S unit. The BMS negotiated correctly over SMBus, charge acceptance began immediately at full rate, and the protection circuit responded normally to a simulated over-discharge event — cutting out cleanly at the low-voltage threshold.
• First cycle after installation: After fitting this cell, run the ThinkPad to hibernate-level cutoff on battery power, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell's actual capacity and clears the false "poor health" warning that routinely appears after any cell swap on this platform.

BIOS reporting poor battery health immediately after swap on ThinkPad T470 and P51S

ThinkPad firmware reads cycle count, charge history, and rated Wh from the battery's EEPROM at boot. A new cell carries factory-default EEPROM values that don't match the laptop's stored learned data from the old battery, so the system flags the health as poor or unknown. This is a data mismatch, not a cell fault. Running one full discharge-to-hibernate followed by a complete uninterrupted charge allows the BIOS learn cycle to write new baseline data to match the installed cell. After one or two full cycles the health status normalises and the warning clears.

ThinkPad shutting down at 20–30% charge shown on the fuel gauge

This happens when the fuel gauge IC's calibration map still references the old cell's discharge curve. Under combined CPU and display load, the actual cell voltage drops faster than the gauge predicts, and the system hits the BMS low-voltage cutoff while the OS still shows charge remaining. The fix is calibration: discharge fully until hibernate triggers, then charge to 100% without interruption — repeat twice if the shutdowns persist. After calibration cycles the gauge IC re-maps the curve to the new cell, and the OS percentage figure tracks actual voltage correctly down to approximately 11.0V at the cutoff knee.