About this replacement
Samsung Galaxy Fold — 3.85V Li-Polymer Replacement Battery (EB-BF901ABU)
This is a 3.85V, 2000mAh Li-Polymer cell that replaces the internal battery in the Samsung Galaxy Fold. It fits the SM-F900J, SM-F9000, SM-F900F, and related SM-F900 variants. Install it when the original cell no longer holds a charge or causes unexpected shutdowns.
- SM-F900 series compatibility: All SM-F900 variants share the same voltage rail, connector pinout, and BMS handshake protocol as the original EB-BF901ABU cell. The fuel gauge IC communicates over the same I2C bus, so the replacement cell pairs without firmware rejection.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an SM-F9000 unit. The BMS accepted the cell immediately, charge current ramped correctly through CC/CV stages, and the protection circuit triggered at expected cutoff thresholds without false trips.
- First-cycle calibration tip: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's actual discharge curve before high-current charging pushes amps into an uncalibrated state.
Why the Fold reports wrong battery percentage after a cell swap
The Galaxy Fold uses a fuel gauge IC that tracks charge state using a learned discharge curve from the old cell. After installing a new cell, that stored curve no longer matches the new cell's characteristics. The IC's coulomb counter starts reporting inaccurate state-of-charge figures — often reading higher than actual. One full slow discharge down to shutdown, followed by a complete uninterrupted charge to 100%, resets the learned curve and restores accurate percentage readings.
Sudden shutdown at 20–30% on the replacement cell
This happens when the new cell's voltage drops below the minimum threshold the modem or foldable display controller will tolerate under peak load — even though the fuel gauge still reads 20–30%. The cell voltage sags sharply during high-draw moments, hitting the BMS undervoltage cutoff at roughly 3.0V per cell before the percentage reaches zero. It is not a faulty battery — it is an uncalibrated fuel gauge reading a flat discharge curve instead of the actual voltage. Run one full slow discharge-charge cycle to recalibrate; shutdowns at low percentage should stop after that.