About this replacement
BLU Studio X Mini — 3.7V Li-ion Replacement Battery (C685543180L)
This is a 3.7V, 1600mAh Li-ion replacement cell for the BLU Studio X Mini smartphone, covering model numbers S0150UU and S0151UU. It replaces OEM part number C685543180L. Fit this cell when the original no longer holds charge through a normal day of use.
- S0150UU and S0151UU compatibility: Both Studio X Mini variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers both. Physical dimensions are 68.20 × 55.65 × 4.30mm, matching the OEM footprint exactly.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Studio X Mini platform. The BMS accepted the cell without error flags, and the charge IC cycled through CC/CV stages cleanly with no premature cutoff.
- First-cycle fuel gauge recalibration: After installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. The fuel gauge IC on the Studio X Mini calibrates its coulomb counter against the new cell's discharge curve on that first pass — skipping this step causes percentage jumps and early-shutdown warnings for the first few days.
Why the Studio X Mini shuts down suddenly at 20–30% after a cell swap
The Studio X Mini's fuel gauge IC stores a discharge curve learned from the original cell. A new cell has a different internal resistance profile, so the IC misjudges the remaining voltage under load. When the modem transmits or the screen peaks brightness, current draw spikes and cell voltage dips below the shutdown threshold — even though the displayed percentage still reads 20–30%. One full discharge cycle lets the IC relearn the curve against the new cell and corrects the shutdown point. After recalibration, the phone should reach a true low-voltage cutoff near 3.4–3.5V before powering off.
Battery percentage jumping erratically after replacement
This is the coulomb counter resetting mid-session because it has no accurate state-of-charge baseline for the new cell. The IC accumulated error over months with the degraded original cell, and those figures carry over to the replacement. Charge the phone to 100% without interruption, then discharge it fully to auto-shutdown in one unbroken session. That single cycle forces the IC to reset its full-scale reference and anchor the counter to real cell capacity — erratic jumps typically stop after that cycle completes.