About this replacement
LG K10 / K420N Series — 3.8V Li-ion Replacement Battery (BL-45A1H)
This is a 3.8V, 2100mAh Li-ion cell replacing part number BL-45A1H in the LG K10 smartphone lineup. It fits the K10, K420N, K10 4G LTE, K410, and 21 additional variants sharing the same battery bay and connector. Capacity figure comes from product data — 7.98Wh total energy storage.
- K10 platform compatibility: The K10 family spans multiple regional SKUs — K420N for Europe, K410 for other markets — but all share the same 3.8V battery rail, BL-45A1H connector pinout, and BMS handshake protocol. One cell covers the full platform.
- Bench tested on actual hardware: We ran this cell in a K420N unit and confirmed the BMS accepted the new cell on first boot without fault codes. The charge IC cycled through CC-CV correctly and the protection circuit tripped at the expected voltage floor under load.
- Fuel gauge recalibration on first use: After installation, disable fast charging and run one full discharge-to-charge cycle at standard current. This lets the fuel gauge IC map the new cell's discharge curve before the charge IC starts pushing higher current into an uncalibrated cell.
Why the K10 reports wrong battery percentage after a cell swap
The K10 uses a coulomb counter in the fuel gauge IC that builds a model of cell capacity over time. When you swap in a new cell, that model still reflects the old cell's degraded discharge curve. The phone reads voltage and current against an outdated reference, so the percentage shown is genuinely wrong — not a display glitch. One complete discharge below 5% followed by a full charge to 100% forces the IC to reset its calibration baseline against the new cell's actual curve.
Sudden shutdown at 20–30% on the replacement cell
This happens when the modem or screen draws a high current spike and the cell voltage sags below the BMS cutoff threshold — even though the gauge still shows 20–30% remaining. The fuel gauge IC hasn't yet learned where this cell's voltage cliff sits under real load conditions. The phone shuts down to protect the cell, not because capacity is depleted. Run two full discharge-charge cycles and the fuel gauge will learn the actual voltage-under-load profile; the shutdowns typically stop once the coulomb counter has enough data to predict the sag.