EB-L1G6LLUC Samsung Galaxy S3 Replacement Battery 3.8V 2100mAh

AT&T Galaxy S 3 — 3.8V Li-ion Replacement Battery (EB-L1G6LLUC)

This is a 3.8V, 2100mAh Li-ion replacement battery for the Samsung Galaxy S 3, sold under the AT&T brand. It fits the Galaxy S III across AT&T variants and uses OEM-matched part numbers including EB-L1G6LVA, EB-L1G6LLK, and EB-L1G6LLA. The cell dimensions are 63.00 x 50.40 x 5.40mm — same footprint as the original.

• Galaxy S 3 variant compatibility: AT&T, unlocked, and carrier-specific Galaxy S III models share the same battery bay geometry and BMS connector pinout. The voltage rail and charge termination logic are identical across these variants, so one cell covers the full S3 lineup.
• Bench tested on actual hardware: We ran this cell on a Galaxy S III through charge-discharge cycles on the bench. The BMS accepted charge termination at 4.35V and held the protection circuit cutoff at the expected low-voltage threshold without tripping prematurely under display and modem load.
• Fuel gauge recalibration on first use: On first installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before the charge IC pushes high current into an uncalibrated cell — skipping this step causes erratic percentage readings early on.

Sudden shutdown at 20–30% on the Galaxy S 3 after a cell swap

The Galaxy S 3's fuel gauge IC retains the discharge curve from the old cell in memory. When the replacement cell hits a voltage point the IC doesn't expect — because the curve hasn't been recalibrated — it signals a low-battery cutoff even though charge remains. The phone shuts down not from actual depletion but from a mismatch between the stored curve and the new cell's real voltage slope. Run one full discharge to automatic shutdown followed by a full charge uninterrupted, and the IC will rewrite its reference curve to match the new cell.

Phone not powering on after the replacement battery sat in storage

Li-ion cells discharged below 2.5V per cell trigger a BMS lockout — the protection circuit opens and blocks current flow to prevent damage from deep discharge. A standard USB charge attempt won't wake a locked-out cell because the charge IC also requires a minimum voltage before it begins the charge sequence. Connect the phone to a wall adapter — not a PC port — and leave it for 15–20 minutes without pressing the power button. The charge IC on a wall adapter delivers a trickle precharge current that can recover the cell above the 2.5V threshold and release the BMS lockout.