About this replacement
Lenovo K800 — 3.7V Li-ion Replacement Battery (BL189)
The BL189 is a 3.7V Li-ion cell rated at 1900mAh (7.03Wh), built to replace the original battery in the Lenovo K800 smartphone. The K800 is an Intel Atom-powered Android device from the early 2010s that uses a removable battery. When the original cell degrades and can no longer hold voltage under screen or modem load, this replacement restores full device function.
- K800 fit confirmed: The BL189 connector, physical footprint (51.90 × 51.00 × 6.00mm), and voltage rail match the K800 battery bay exactly. No adapters or modifications required — the BMS handshake negotiates with the K800's charge IC as expected.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the K800 platform. The BMS held charge cutoff at the correct upper voltage threshold and did not trip under normal screen-on and modem-active load conditions.
- Fuel gauge recalibration on first use: After installation, run one full discharge down to auto-shutdown, then charge uninterrupted to 100% before using the device again. The K800's coulomb counter is calibrated to the old cell — skipping this step causes the percentage readout to drift or report inaccurate levels from day one.
Sudden shutdown at 20–30% on the BL189 replacement cell
The K800 shuts down mid-use because the phone's fuel gauge IC is still referencing the discharge curve of the worn original cell. When the new cell hits a voltage point the old curve mapped to 20–30%, the system triggers an emergency cutoff — even though real capacity remains. The fix is a full discharge-charge calibration cycle immediately after installation. After one complete cycle, the coulomb counter resets its reference and the percentage readout stabilises.
Device not powering on after the BL189 sat in storage
Li-ion cells that sit uncharged for extended periods can drop below 2.5V per cell, which triggers BMS lockout — the pack refuses to accept a charge or power the device as a protection measure. Connect the K800 to a wall charger and leave it undisturbed for 15–20 minutes before attempting to power on. Most BMS circuits will accept a trickle pre-charge at this stage and begin recovery. If the charge LED does not activate within 30 minutes, check that the charger output is at least 5V 1A.