About this replacement
LG Optimus G2 Mini D620 Series — 3.8V Li-ion Replacement Battery (BL-59UH)
This is a 3.8V, 2400mAh Li-ion replacement battery for the LG Optimus G2 Mini. It fits the D620, D620R, and D620J variants along with four additional D620 sub-models. Capacity comes from product data: 2400mAh / 9.12Wh.
- D620 variant coverage: All D620 sub-models share the same voltage rail, connector pinout, and BMS handshake protocol, which is why a single cell — BL-59UH — covers the full range. The charge IC communicates the same way across all regional variants.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a D620 unit. The BMS accepted the handshake without fault, and the charge IC held current limits within spec across the full charge curve.
- First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.
Sudden shutdown at 20–30% on the BL-59UH replacement cell
This happens because the fuel gauge IC is still reading the old cell's voltage curve. The new cell hits a steeper voltage cliff under load — modem transmit or screen brightness spike — before the gauge catches up. The BMS cuts power to protect the cell even though the OS is showing charge remaining. One full discharge down to auto-shutdown, followed by an uninterrupted charge to 100%, resets the coulomb counter and eliminates the false floor.
OS reporting wrong battery percentage after cell swap
The Android fuel gauge IC holds calibration data from the original cell in non-volatile memory. When a new cell goes in, that stored curve no longer matches the actual cell chemistry, so percentage jumps erratically or reads high and drops fast. The fix is one full uninterrupted cycle: drain the phone until it shuts itself off, then charge straight to 100% without interruption. After that cycle, the coulomb counter maps to the new cell and percentage readings stabilise.