About this replacement
Samsung Galaxy Jean / A6+ 2018 — 3.85V Li-Polymer Replacement Battery (EB-BJ805ABE)
This is a 3.85V, 3400mAh Li-Polymer cell that replaces OEM part EB-BJ805ABE in the Samsung Galaxy Jean, Galaxy A6+ 2018 Duos, Galaxy A6 Plus 2018 Duos, and Galaxy A9 Star Lite, among others. It matches the original cell footprint at 91.10 × 45.50 × 4.90mm and uses the same flex connector the motherboard expects. Capacity is rated at 3400mAh (13.09Wh).
- Galaxy A6+ and Jean platform compatibility: These models share the same 3.85V power rail, identical flex connector pinout, and the same BMS handshake protocol — which is why one cell covers the full variant range including Duos SKUs.
- Bench tested on actual hardware: We ran this cell on a Galaxy A6+ 2018 board. The BMS accepted the cell without error flags, charge IC stepped through trickle, CC, and CV phases normally, and the fuel gauge IC logged a full cycle without dropping to safe mode.
- Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard current. This gives the fuel gauge IC a clean discharge curve from the new cell before high-current charging pushes against an uncalibrated state-of-charge estimate.
Why the Galaxy Jean reports wrong battery percentage after a cell swap
Samsung's fuel gauge IC builds a discharge curve from historical cycle data stored against the old cell. When you swap the physical cell, that learned curve no longer matches the new cell's actual voltage-to-capacity relationship. The OS reads voltage from the IC and maps it to a percentage using the stale curve — so 40% displayed might be 25% actual. One full discharge down to automatic shutdown, followed by a full charge to 100%, forces the coulomb counter to reset and write a new baseline curve.
Sudden shutdown at 20–30% on the Galaxy A6+ after replacement
This happens when the cell voltage drops below the modem or display load threshold faster than the fuel gauge IC predicted — a voltage cliff. Under peak draw from LTE transmission or screen-on brightness, the cell briefly sags below 3.4V and the BMS trips a protective cutoff before the displayed percentage reaches zero. It is not a fault with the cell itself. Run the first full recalibration cycle, then check that the shutdown stops occurring above 15% — if it persists, confirm the flex connector is fully seated and re-check contact resistance at the board-side pads.