About this replacement
Samsung Galaxy Z Flip F707U / 5G — 3.86V Li-Polymer Replacement Battery
This 3.86V, 630mAh (2.43Wh) Li-Polymer cell replaces the cover display battery in the Samsung Galaxy Z Flip F707U and Galaxy Z Flip 5G (SM-F707U1, SM-F707W). It fits the compact secondary cell position inside the folding chassis. Use this part when the original cell degrades and the phone begins shutting down early or reporting erratic charge levels.
- F707U and 5G variant fitment: The F707U, SM-F707U1, and SM-F707W all share the same 3.86V cell format and connector pinout. The fold hinge imposes tight dimensional tolerances — this cell matches the 42.70 × 22.60 × 5.30mm envelope required to close cleanly without pressure on the flex cable.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the F707U platform. The BMS accepted the cell without handshake errors, and the charge IC completed a full constant-current to constant-voltage taper without fault flags.
- Fuel gauge recalibration on first use: After installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter locks in its reference points. Skipping this step causes the OS to report inaccurate percentages for the first several cycles.
Sudden shutdown at 20–30% on the Z Flip after a cell swap
The Galaxy Z Flip runs two power-hungry loads simultaneously — the foldable OLED and the 5G modem. When either ramps current draw, the cell voltage must hold above the BMS cutoff threshold. A new cell with an uncalibrated fuel gauge IC can appear to have 25% remaining while the actual open-circuit voltage is already near 3.5V under load. The BMS trips the cutoff, and the phone shuts down without warning. One full slow-charge cycle recalibrates the coulomb counter and eliminates most premature cutoffs.
USB-PD fast charge not recognised on first cycle after installation
On the first connection after a cell swap, the charge IC may reject the fast-charge handshake and fall back to 5W standard charging. This happens because the BMS has not yet established a baseline impedance reading for the new cell. It is not a fault with the charger or cable. Complete one full charge at standard rate — on the second connection, the USB-PD negotiation proceeds normally and fast charge engages.