AT&T Galaxy S III EB-L1G6LLA Replacement Battery 3.8V 2100mAh

AT&T Galaxy S III — 3.8V Li-ion Replacement Battery (EB-L1G6LLA)

This is a 3.8V, 2100mAh Li-ion replacement battery for the Samsung Galaxy S III smartphone. It fits all Galaxy S III variants, including the Galaxy S3 and Galaxy SIII. The OEM part number EB-L1G6LLA confirms direct fitment with the original battery slot and connector.

• Galaxy S III variant coverage: Samsung sold the Galaxy S III across multiple carriers under slightly different model designations, but all share the same battery bay dimensions, 3.8V cell voltage, and connector pinout. This cell covers all of those variants with no modification.
• Bench tested on actual hardware: We ran this battery on a Galaxy S III unit and confirmed BMS handshake with the device's charge IC, stable voltage delivery under simultaneous display and LTE modem load, and correct recognition by the Android battery service layer.
• Fuel gauge recalibration on first use: After installing this cell, disable fast charging if available and run one complete discharge-charge cycle at standard rate. The Galaxy S III's fuel gauge IC was calibrated to the discharge curve of the old cell — one full slow cycle aligns the coulomb counter to the new cell before the charge IC pushes higher current.

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

This is a voltage cliff issue, not a defective cell. The fuel gauge IC still references the old cell's discharge curve, so it reports 25% remaining while the actual cell voltage has already dropped below the threshold the modem and display require under combined load. When the processor, LTE radio, and screen all draw simultaneously, the cell can't sustain voltage, and the device shuts down as a protection response. Run one full discharge to automatic shutdown followed by a full charge — the coulomb counter will remap its reference points against the new cell's actual curve.

Galaxy S III not powering on after the replacement battery sat in storage

Li-ion cells in storage self-discharge slowly. If the cell drops below 2.5V per cell, the BMS enters a lockout state to prevent cell damage, and the phone will show no response at all — no boot, no charging indicator. Connect the phone to a wall charger, not a USB port, and leave it for 15–20 minutes without attempting to power on. The charge IC needs to trickle enough current through the BMS lockout threshold before normal charging resumes. If the charging indicator appears, the cell has recovered above the lockout floor — typically around 2.8V — and the device will charge normally from that point.