About this replacement
Samsung Galaxy Grand 2 / SM-G7102 — 3.8V Li-ion Replacement Battery (EB-B220AC)
This is a 3.8V, 2100mAh lithium-ion replacement battery for the Samsung Galaxy Grand 2 and Galaxy Grand 2 Duos smartphones. It fits SM-G7102, SM-G7106, and related SM-G71xx variants that share the EB-B220AC specification. Swap it in when the original cell can no longer hold a usable charge through a normal day.
- SM-G7102 and SM-G7106 compatibility: Both variants run the same 3.8V nominal rail and use the same physical connector and BMS handshake. One cell covers the full Grand 2 Duos line without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a Grand 2 unit. The protection circuit held the charge cutoff at 4.35V and the discharge cutoff triggered correctly before voltage collapsed under load.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before feeding it high current into an uncalibrated state.
Why the Grand 2 reports wrong battery percentage after a cell swap
The Grand 2 uses a coulomb counter that builds its fuel gauge model against the original cell's impedance curve over many cycles. When a new cell goes in, that model no longer matches reality. The phone may report 80% while the cell is near full, or show 30% and then drop straight to zero. One full discharge down to automatic shutdown, followed by an uninterrupted charge to 100%, forces the IC to reset its learned curve against the new cell. After that single cycle, percentage readings stabilise.
Sudden shutdown at 20–30% on the replacement cell
This happens when the modem radio or display pulls a current spike the cell cannot sustain at that state of charge. Voltage sags below the BMS cutoff threshold — typically around 3.0V under load — and the phone shuts off even though the fuel gauge still shows charge remaining. It is not a faulty battery; it is the fuel gauge IC working from a miscalibrated curve. Run the full recalibration cycle described above. If shutdown continues after one full cycle, check that the battery contacts on the device chassis are clean and making firm contact.