About this replacement
BlackView Ultra / A6 — 3.7V Li-ion 1850mAh Replacement Battery
This is a 3.7V Li-ion cell rated at 1850mAh (6.85Wh), built to fit the BlackView Ultra and A6 smartphones. It replaces a degraded original cell that no longer holds usable charge. Physical dimensions are 74.20 × 58.04 × 4.28mm — confirm these against your existing cell before installation.
- Ultra and A6 platform fit: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol, which is why one cell covers both. The fuel gauge IC on each device reads the same charge curve from this chemistry.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on the Ultra. The BMS accepted the cell without a fault flag, and charge termination triggered correctly at 4.2V with no thermal event.
- First-cycle fast charge tip: On first use after installation, disable fast charging and complete one full discharge-charge cycle at standard rate. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.
Sudden shutdown at 20–30% on the BlackView Ultra after a cell swap
This is a voltage cliff issue, not a capacity problem. Under high-draw loads — mobile data, screen at full brightness, GPS — the new cell's voltage drops faster than the fuel gauge IC expects based on its old calibration map. When cell voltage falls below the BMS cutoff threshold, the phone shuts down even though the percentage display still reads 20–30%. The fix is one full calibration cycle: discharge to automatic shutdown, then charge uninterrupted to 100% at standard rate.
OS reporting erratic or incorrect battery percentage after replacement
The coulomb counter in the BlackView Ultra's fuel gauge IC builds its percentage model against the old cell's impedance and discharge curve. Drop in a new cell and those reference values no longer match the actual cell state. The result is percentage jumps, stalled readings, or a figure that disagrees with real remaining capacity. Run two complete discharge-to-shutdown and full-charge cycles without interruption — the fuel gauge IC resets its learned curve by the end of the second cycle and readings stabilise.