Lenovo BL198 Replacement Battery 3.7V 2000mAh Li-ion

Lenovo S880 / K860 Series — 3.7V Li-ion Replacement Battery (BL198)

This is a 3.7V, 2000mAh Li-ion cell that replaces the original BL198 battery in the Lenovo S880, S880i, K860, and K860i smartphones. If your phone is shutting down early, refusing to charge past a certain point, or barely lasting through a morning, the original cell has degraded past the point of recovery. This battery restores the voltage rail the phone's hardware expects.

• S880 / K860 platform fit: The S880, S880i, K860, and K860i all share the same BL198 form factor — identical connector pinout, cell dimensions (73.20 × 63.48 × 4.10mm), and BMS handshake voltage. One replacement cell covers the full range without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on BL198-compatible hardware and confirmed the BMS accepted the cell without triggering a fault code at cutoff. Charge termination voltage held at the expected 4.2V ceiling.
• Fuel gauge recalibration on first cycle: After fitting this cell, disable fast charging and run one complete discharge-to-charge cycle at standard rate. The fuel gauge IC on these Lenovo devices calibrates its coulomb counter against the actual discharge curve — skipping this step causes erratic percentage readings for the first several days.

Sudden shutdown at 20–30% on the S880 after a cell swap

This is a voltage cliff issue, not a capacity problem. When the modem fires at full power during a call or data burst, it pulls current the new cell struggles to deliver if the fuel gauge IC is still calibrated to the old cell's discharge curve. The phone's protection circuit interprets the voltage sag as a depleted cell and shuts the device down. Run two full discharge-charge cycles at standard charge rate and the fuel gauge will remap to the new cell — shutdowns at false percentages stop once the coulomb counter has accurate reference points from the actual cell chemistry.

Phone reads 100% but drops to 15% within minutes of unplugging

This symptom means the fuel gauge IC is still reading the old cell's internal resistance profile, not the new cell's. The percentage display is driven by a software model, not a live voltage read — so the mismatch between expected and actual discharge curves causes the counter to jump. Force a full charge to 4.2V using the stock charger, then let the phone discharge without interruption to the point it shuts itself off. Plug in and charge uninterrupted to 100%. After that single calibration cycle, the percentage tracking stabilises.