LG Wing 5G BL-T52 Replacement Battery 3.87V 3900mAh

LG Wing 5G — 3.87V Li-Polymer Replacement Battery (BL-T52)

This is a 3.87V, 3900mAh Li-Polymer replacement battery for the LG Wing 5G smartphone. It fits the Wing 5G dual-screen rotating device and its variants, including F100VMY, F100, and LMF100TMK. OEM part number BL-T52 cross-references directly to this cell.

• Wing 5G and F100 series fit: These models share the same battery bay geometry, BMS connector pinout, and 3.87V nominal voltage rail. The BL-T52 footprint — 77.74 × 63.90 × 4.72mm — is consistent across all variants in this lineup, so one cell covers the full range.
• Bench tested on actual hardware: We ran this cell through charge-discharge cycles on a Wing 5G unit and monitored the BMS handshake. The protection circuit tripped correctly at low-voltage cutoff, and the charge IC accepted the cell without thermal flags or fault codes.
• Fuel gauge recalibration on first use: After installation, disable fast charging for one full discharge-charge cycle. The fuel gauge IC is calibrated to the old cell's discharge curve. Running one slow cycle first lets the coulomb counter map the new cell before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the Wing 5G after a cell swap

This happens when the fuel gauge IC still holds the old cell's voltage-to-capacity curve in memory. The new cell hits a voltage cliff under 5G modem or dual-screen load that the OS doesn't recognise as low — until the phone cuts off hard. The fix is one full slow-charge cycle with fast charging disabled, which forces the coulomb counter to relearn the actual discharge curve. After that cycle, the reported percentage tracks the real cell state correctly.

USB-PD fast charge not activating after replacement

On the first charge cycle after installation, the charge IC may not negotiate fast-charge protocols with a new cell — this is normal BMS behaviour, not a defective unit. The controller holds back high current until it has verified cell impedance and temperature within safe thresholds. Plug in via USB-PD and let the first full cycle complete at standard charge rate. Fast charge typically re-engages automatically from the second cycle onward once the BMS has cleared its initial validation pass.