About this replacement
LG V510N / V50S ThinQ 5G — 3.87V Li-Polymer Replacement Battery (BL-T42)
This is a 3.87V, 3350mAh Li-Polymer replacement battery for the LG V510N, V50S ThinQ 5G, and compatible models using the BL-T42 cell. It restores power to a phone that no longer holds a usable charge due to a degraded original cell. Voltage and capacity match the OEM specification exactly.
- V510N and V50S ThinQ 5G platform fit: Both models share the same battery bay geometry, connector pinout, and BMS handshake protocol — the BL-T42 part number covers this entire platform because the charge IC on each device negotiates with the same cell-side BMS logic.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on V50S ThinQ 5G hardware. The BMS accepted the charge IC handshake cleanly, and the protection circuit tripped correctly at the undervoltage threshold with no false cutoffs mid-cycle.
- Fuel gauge recalibration after install: On first use, disable fast charging and run one full discharge down to automatic shutdown, then charge to 100% on standard charging. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter locks in its reference points.
Sudden shutdown at 20–30% on the BL-T42 replacement cell
A new cell has a slightly different discharge curve than the aged cell the fuel gauge IC was calibrated against. When the phone's SoC pulls high current for 5G modem activity or the display, the cell voltage drops sharply at a threshold the fuel gauge wasn't expecting — it triggers an emergency shutdown even though the reported percentage looks safe. This is a calibration gap, not a defective battery. One full discharge-to-shutdown cycle followed by a full charge resets the coulomb counter and resolves the early cutoff.
USB-PD fast charge not activating on the first cycle after replacement
The LG V50S ThinQ 5G charge IC runs a brief handshake with the battery BMS before enabling the high-current USB-PD charging path. On a fresh cell, the BMS sometimes holds the charge rate at standard levels for the first cycle while it verifies cell impedance is within acceptable range. This is normal behaviour — not a charger or port fault. After one complete standard charge cycle, the fast charge protocol activates correctly on subsequent charges.