Motorola FC40 Moto G 3rd gen Replacement Battery 3.8V 2300mAh

Motorola Moto G 3rd Gen — 3.8V Li-Polymer Replacement Battery (FC40 / SNN5965A)

This is a 3.8V, 2300mAh Li-Polymer replacement battery for the Motorola Moto G 3rd gen (Moto G3, Moto G3 Dual SIM, Moto G 2015). It replaces OEM part numbers FC40, SNN5965A, FC40-T, and SNN5967A. Swap it in when the original cell no longer holds charge through a normal day of use.

• Moto G3 platform compatibility: All variants in the Moto G 3rd gen lineup — single SIM, Dual SIM, and the 2015 retail release — share the same battery bay geometry, connector pinout, and BMS handshake protocol. One cell fits all of them without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge passes on a Moto G3 unit. The BMS accepted the cell without fault codes, thermal cutoff did not trigger during charging, and the charge IC held steady current through the bulk phase.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins. Skip this step and the coulomb counter stays calibrated to the old cell — percentage readings will drift.

Sudden shutdown at 20–30% on a replacement cell

This is a voltage cliff problem, not a capacity problem. Under modem transmission load or screen-on brightness, the cell's internal resistance causes voltage to sag below the system's cutoff threshold even though the fuel gauge still shows 20–30%. The phone interprets the voltage drop as a dead battery and shuts down. The fix is one full calibration cycle — drain the phone to automatic shutdown, then charge uninterrupted to 100% without fast charging. After that cycle, the fuel gauge IC maps the new cell's actual voltage curve and the false shutdowns stop.

Phone won't power on after sitting in storage with this battery installed

Li-Polymer cells self-discharge in storage. If the cell drops below approximately 2.5V, the BMS enters lockout mode to prevent damage and the phone will not respond to the power button. Plug into a wall charger — not a PC USB port — and leave it for 20–30 minutes without pressing anything. The charge IC needs to trickle current into the cell until voltage recovers above the BMS unlock threshold before the phone will boot. If the charge LED does not illuminate within five minutes of connecting the charger, try a different cable and confirm the charger delivers at least 5V 1A.