LG X410 BL-T36 Replacement Battery 3.85V 2900mAh

LG Phoenix Plus / X410 Series — 3.85V Li-Polymer Replacement Battery (BL-T36)

This is a 3.85V, 2900mAh Li-Polymer replacement cell for the LG X410, X410AS, Phoenix Plus, and Phoenix Plus LTE-A. It matches the OEM part number BL-T36 and fits the same physical footprint at 66.96 × 55.00 × 5.10mm. Install it when the original cell no longer holds a charge or the phone shuts down unexpectedly under load.

• X410 and Phoenix Plus platform fit: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. A single cell — BL-T36 — covers the full X410 variant lineup because LG used one power architecture across these SKUs.
• Bench tested on actual hardware: We ran this cell through full charge and load cycles on the X410 platform. The BMS negotiated charge termination correctly, and the protection circuit tripped at the expected undervoltage threshold without nuisance cutoffs.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the X410 after a cell swap

The X410's power IC reads cell voltage and maps it to a percentage using a stored curve from the original cell. A new cell has a slightly different voltage-to-capacity curve, so the fuel gauge IC can report 25% while the actual cell voltage has already dropped below the modem's minimum rail. Under a burst load — a call, a 4G handoff, screen-on — current demand spikes and voltage sags below the cutoff threshold instantly. Run one full discharge cycle down to automatic shutdown, then charge uninterrupted to 100% to force a curve resync. After that cycle, shutdowns below 20% should stop.

USB fast charging not engaging after replacement

On the first charge cycle with a new BL-T36 cell, the charge IC on the X410 may not negotiate the fast-charge handshake correctly — it defaults to standard 5V/1A input instead. This happens because the charge controller reads cell impedance before allowing elevated current, and a new cell at room temperature can present higher impedance than the controller's threshold allows. Plug in with the original LG wall adapter, let the first charge complete fully without interrupting it, and fast charging typically activates from the second cycle onward. If it still does not engage, check that the USB-C port contacts are clean and the cable is rated for fast charge.