Samsung Galaxy S II EB-L102GBK Replacement Battery 3.7V 1300mAh

Samsung Galaxy S II — 3.7V Li-ion Replacement Battery (EB-L102GBK)

This is a 3.7V, 1300mAh Li-ion replacement battery for the Samsung Galaxy S II smartphone. It fits the GT-I9100 and related Galaxy S2 variants that use the EB-L102GBK cell. The battery slides into the original compartment and connects via the same three-contact puck on the rear housing.

• GT-I9100 and Galaxy S2 variants: These models share the same battery bay dimensions, voltage rail, and contact pinout. The EB-L102GBK also cross-references as EB-L1A2GBU and GH43-03539A — Samsung used multiple part numbers across production runs, but all draw from the same 3.7V nominal cell spec and BMS handshake.
• Bench tested on actual hardware: We ran this cell on a GT-I9100 unit under screen-on load with Wi-Fi and mobile data active. The BMS held stable cutoff thresholds and the charge IC accepted a full CC/CV cycle without tripping an error state.
• Fuel gauge recalibration on first install: After fitting this cell, run one complete discharge-to-charge cycle with fast charging disabled. The Galaxy S II's fuel gauge IC was calibrated against the original cell's discharge curve. A full slow cycle lets it re-map against this new cell before you resume normal charging patterns.

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

The GT-I9100 runs a combined modem and display load that spikes current draw hard at 20–30% reported charge. A new cell with an uncalibrated fuel gauge IC can report 25% while the actual cell voltage has already dropped below the BMS cutoff threshold under that spike. The BMS reads a real undervoltage condition and kills the rail instantly — the OS never sees it coming. One full discharge-to-cutoff cycle, followed by a slow charge to 100%, resets the coulomb counter and tightens the IC's voltage-to-percentage mapping.

Galaxy S II not powering on after the battery sat in storage

Li-ion cells self-discharge in storage. If this battery shipped or sat unused for several months, the cell voltage may have dropped below 2.5V — the threshold where most BMS circuits lock out to prevent cell damage. The Galaxy S II will show nothing on screen, and a standard wall charge will not recover it. Connect the battery to a USB charger and leave it for 20–30 minutes before pressing power; most BMS circuits have a trickle recovery path that accepts low current at voltages above 2.0V and will unlock the main charge circuit once the cell climbs back above 2.8V.