EB-BG885ABU Samsung Galaxy A8 Star Replacement Battery 3.85V 3600mAh

Samsung Galaxy A8 Star / A9 Star — 3.85V Li-Polymer Replacement Battery (EB-BG885ABU)

This is a 3.85V, 3600mAh Li-Polymer replacement battery for the Samsung Galaxy A8 Star and Galaxy A9 Star smartphones. It carries OEM part number EB-BG885ABU and fits SM-G8858, SM-G885F/DS, and related variants. Capacity figures come from the product data — 13.86Wh total energy.

• A8 Star and A9 Star shared platform: Both devices run the same Snapdragon 660 voltage rail and use an identical physical connector, BMS pinout, and charge IC handshake — which is why a single cell covers the full model range listed above.
• Bench tested on actual hardware: We cycled this cell through charge, full discharge, and a fast-charge initiation sequence. The BMS held cutoff cleanly at both ends and accepted the charge IC handshake without a second-cycle reset.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one complete discharge-charge cycle at standard speed. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated counter.

Sudden shutdown at 20–30% on the Galaxy A8 Star after a cell swap

This happens because the fuel gauge IC still holds the discharge curve of the old, degraded cell. When the new cell hits a voltage point that the old curve mapped to 20–30%, the IC signals a low-voltage emergency and the phone cuts power. The modem and display together pull enough current at that state of charge to cause a brief voltage sag — the IC reads that sag as a cliff and shuts down. One full discharge-charge cycle at standard speed forces the coulomb counter to relearn the new cell's actual curve and eliminates the false cutoff.

USB fast charge not activating on first cycle after replacement

Samsung's Adaptive Fast Charging handshake runs a brief negotiation between the charge IC and the BMS on every new cell's first cycle. If the BMS has not yet completed its initial calibration pass, the charge IC defaults to 5V standard input and fast charge appears inactive in the battery settings menu. This is not a fault with the cell or the charger. Fully discharge the phone to auto-shutdown, then charge uninterrupted to 100% — fast charging activates normally from the second cycle onward.