About this replacement
BLU C6 — 3.8V Li-Polymer 2500mAh Replacement Battery (C766243250L)
This 3.8V Li-Polymer battery replaces the original cell in the BLU C6 smartphone (model C0090P). It carries a 2500mAh / 9.5Wh capacity — matching the factory spec. Fit confirmed for the C6 platform against OEM part number C766243250L.
- C6 / C0090P platform fit: Both model numbers share the same physical footprint (76.50 × 62.00 × 5.00mm), connector pin-out, and BMS voltage thresholds — a single cell revision covers both variants without adapter or modification.
- Bench tested on actual hardware: We ran a full charge-discharge cycle on the BLU C6 platform. The BMS accepted the cell without fault codes, charge termination triggered correctly at 4.35V, and low-voltage cutoff engaged at 3.0V as expected for a Li-Polymer cell in this voltage class.
- Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% uninterrupted. This gives the fuel gauge IC one clean cycle to map the new cell's discharge curve before fast-charge current is applied to an uncalibrated cell.
Why the BLU C6 reports wrong battery percentage after a cell swap
The BLU C6 uses a coulomb counter that tracks charge in and out relative to a stored discharge curve — one built against the original cell's impedance profile. When a new cell goes in, that curve no longer matches, so the IC reports inaccurate state-of-charge figures, sometimes jumping 10–15% in either direction. The fix is one full discharge-charge cycle with the screen on and mobile data active — real-world load forces the coulomb counter to sample across the full voltage range of the new cell. After that cycle, percentage reporting stabilises. If it doesn't settle within two cycles, check that the battery connector is fully seated and the cell voltage reads at least 3.7V at rest.
Sudden shutdown at 20–30% on the BLU C6
This is a voltage cliff — not a capacity problem. When the modem transmits or the screen runs at full brightness, instantaneous current draw spikes and pulls the cell voltage below the BMS cutoff threshold faster than the fuel gauge can track. A new cell can show this on the first few cycles if the fuel gauge IC is still reading from an old discharge map. Run two full discharge-charge cycles to let the IC recalibrate. If shutdowns persist past cycle two, check resting cell voltage with the phone off — it should read above 3.6V; anything below 3.4V at rest indicates a cell quality issue.