Samsung Galaxy S10 5G EB-BG977ABU Replacement Battery 3.85V 4000mAh

Samsung Galaxy S10 5G — 3.85V Li-Polymer Replacement Battery (EB-BG977ABU)

This 3.85V, 4000mAh Li-Polymer battery replaces part number EB-BG977ABU in the Samsung Galaxy S10 5G. It fits the SM-G977 series, including SM-G977V and SM-G977U variants. Swap it in when the original cell no longer holds a charge or shuts down unexpectedly under load.

• SM-G977 series compatibility: All SM-G977 variants share the same physical cell pocket, connector pinout, and BMS handshake protocol. The voltage rail runs at 3.85V nominal, and the charge IC expects a lithium-polymer cell with matched impedance — this cell meets both requirements.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on an SM-G977V. The BMS accepted the cell without error flags, the charge IC stepped through trickle, CC, and CV phases cleanly, and coulomb counter registration completed after one full cycle.
• Fuel gauge recalibration after installation: On first use, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated reference table.

Sudden shutdown at 20–30% on the replacement cell

This happens because the fuel gauge IC still references the old cell's discharge curve. When the S10 5G hits a peak load — 5G modem handoff, sustained screen brightness, or GPS — the new cell's voltage drops faster than the old curve predicts. The phone reads 25% but the cell voltage has already fallen below the BMS protection threshold. Run one full discharge to 1% under normal use, then charge to 100% without interruption, and the coulomb counter re-anchors to the new curve.

USB-PD fast charge not activating after the cell swap

After a cell replacement, the charge IC on the S10 5G sometimes defaults to standard 5V input and won't negotiate USB-PD fast charge on the first cycle. This is a handshake timing issue between the new BMS and the device's charge controller — not a cable or charger fault. Power the phone fully off, connect the original Samsung fast charger, then power back on. If fast charge still doesn't activate, complete one standard-rate charge cycle first, then retry.