Motorola Moto G 5G 2025 RA50 Replacement Battery 3.91V 4900mAh

Motorola Moto G 5G 2025 / G15 NFC 2025 — 3.91V Li-Polymer Replacement Battery (RA50)

This is a 3.91V, 4900mAh (19.16Wh) lithium-polymer cell for the Motorola Moto G 5G 2025 and Moto G15 NFC 2025 smartphones, including variants XT2521-1 and XT2521-2. It replaces OEM part number RA50. Use this when the original cell no longer holds charge, shuts down unexpectedly, or swells.

• XT2521 platform compatibility: The XT2521-1 and XT2521-2 share the same voltage rail, connector pinout, and BMS handshake as the G15 NFC 2025 variant — one cell fits all four models without modification.
• Bench tested on actual hardware: We cycled this cell on an XT2521 unit and confirmed the BMS accepted the cell without fault codes, the charge IC stepped through CC/CV phases correctly, and the fuel gauge IC logged capacity within spec.
• First-cycle calibration on the RA50 cell: After installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes into an uncalibrated state — skipping this step is the main cause of erratic percentage readings after a cell swap.

Sudden shutdown at 20–30% on the Moto G 5G 2025 after a cell swap

This happens because the fuel gauge IC is still running the discharge curve from the old degraded cell. When the new RA50 cell hits a voltage region the IC wasn't expecting, it miscalculates the remaining capacity and triggers a low-voltage shutdown. The modem and display together pull enough current to expose the mismatch quickly — you'll see it most often during calls or video. One full uninterrupted discharge from 100% to automatic shutdown, followed by a full charge, resets the coulomb counter and resolves the cutoff.

USB-PD fast charge not activating on the first cycle after replacement

On the first cycle, the charge IC may not negotiate the fast-charge protocol until it completes one baseline CC/CV charge at standard rate. The new BMS needs to confirm cell voltage is stable before it allows higher current draw. If the charger shows standard charging only, let the first cycle finish at the lower rate — do not swap chargers or cables mid-cycle. Fast charge typically activates automatically from the second cycle onward once the BMS has confirmed the cell's baseline impedance.