About this replacement
LG G7 ThinQ — 3.85V Li-Polymer Replacement Battery (BL-T39)
This is a 3.85V, 2900mAh Li-Polymer replacement battery for the LG G7 ThinQ smartphone. It replaces OEM part BL-T39 (also listed as EAC63878401) and fits the G7 ThinQ, G7 ThinQ LTE-A, LMG710AWMH, and the Judy platform variants. Install this when the original cell no longer holds a charge or causes unexpected shutdowns.
- G7 ThinQ platform fit: The G7 ThinQ, G7 ThinQ LTE-A, and LMG710AWMH variants all share the same battery bay geometry, connector pinout, and BMS handshake protocol — one cell design covers the full lineup without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the G7 ThinQ platform. The BMS accepted the cell without fault flags, charge termination triggered correctly at 4.35V, and the fuel gauge IC tracked state-of-charge without erratic jumps after one full calibration cycle.
- First-cycle fast charge tip: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current fast charging pushes into an uncalibrated cell.
Why the G7 ThinQ reports wrong battery percentage after a cell swap
The G7 ThinQ uses a coulomb-counting fuel gauge IC that builds its state-of-charge model against the original cell's discharge curve. Swap the cell, and that model no longer matches the new cell's chemistry profile. The IC keeps referencing its old calibration data, so it reports inaccurate percentages — often reading high and then dropping fast. One complete discharge down to automatic cutoff followed by a full charge to 100% forces the IC to rewrite its reference curve against the new cell.
Sudden shutdown at 20–30% remaining on the G7 ThinQ
This is a voltage cliff failure, not a capacity failure. Under high instantaneous load — modem transmitting, display at full brightness, GPS active — the cell voltage sags below the BMS cutoff threshold even though the fuel gauge still shows charge remaining. An aged or weakened cell cannot sustain voltage under that combined draw. If this happens on a new replacement cell, run the fuel gauge recalibration cycle first. If shutdowns persist after calibration, check that the connector is fully seated — a partially connected cell increases internal resistance and accelerates voltage sag under load, triggering cutoff earlier.