LG Velvet BL-T47 Replacement Battery 3.85V 4050mAh

LG Velvet Series — 3.85V Li-Polymer Replacement Battery (BL-T47)

This is a 3.85V, 4050mAh Li-Polymer cell built to replace the original BL-T47 in the LG Velvet and Velvet 5G smartphones. It fits models including LMG900TM and G900TMY, along with 21 additional Velvet variants. Capacity matches the factory spec at 15.59Wh.

• Velvet and Velvet 5G compatibility: Every Velvet variant in this fit list shares the same 3.85V power rail, physical cell footprint (79.42 × 59.70 × 4.70mm), and BL-T47 connector pinout — so one cell covers the full lineup without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Velvet platform. The BMS handshake completed correctly, charge IC accepted the cell without flagging an incompatible source, and cutoff voltage triggered at the expected threshold.
• First-cycle fast charge protocol: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current fast charging pushes current into an uncalibrated cell.

Why the Velvet reports wrong battery percentage after a cell swap

The Velvet uses a coulomb counter and fuel gauge IC that builds a model of the cell's discharge curve over time. When you swap in a new BL-T47, that stored model no longer matches the new cell's actual voltage-to-capacity curve. The IC keeps reading against the old curve, so the percentage shown on screen drifts — often reading 100% too quickly or dropping suddenly at the low end. One full discharge to shutdown followed by an uninterrupted charge to 100% forces the IC to relearn the new curve.

Sudden shutdown at 20–30% on a replacement cell

This happens when the modem, display, or both spike current draw faster than the cell can sustain voltage under load. Even with 20% reported remaining, the cell voltage collapses below the BMS cutoff threshold — typically around 3.0V — and the phone shuts off to protect the cell. The fuel gauge IC hasn't yet mapped where that voltage cliff sits on the new cell. Run two full discharge-charge cycles without fast charging, then check whether the shutdowns persist at the same percentage.