BLU Charleston C4C08T Replacement Battery 3.7V 750mAh

BLU Charleston / Click Series — 3.7V Li-ion Replacement Battery (C4C08T)

This is a 3.7V, 750mAh Li-ion cell that replaces the original battery in BLU Charleston, Click, Click Lite, Deco Mini, and related models. It fits phones using OEM part numbers C4C08T, C4C50T, C4C60T, and C4C85T. Physical dimensions are 53.00 × 34.00 × 4.80mm — measure your existing cell before installing.

• Charleston and Click series fit: These models share the same removable cell format, connector tab position, and 3.7V nominal voltage rail. The BMS on each device accepts this cell's charge profile without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on BLU series hardware. The BMS accepted the new cell without error flags, and charge termination cut off cleanly at the correct upper threshold.
• Fuel gauge recalibration after swap: On first use after installation, run one full discharge down to auto-shutoff, then charge to 100% uninterrupted. This lets the fuel gauge IC map its reference curve to the new cell before reporting percentage to the OS.

Why the BLU Charleston reports wrong battery percentage after a cell swap

The fuel gauge IC in these phones stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches actual cell behaviour, so the reported percentage drifts — often reading high and then dropping sharply. The IC needs at least one uninterrupted full cycle to recalibrate its coulomb counter against the new cell's discharge profile. Until that cycle completes, percentage readings are unreliable. Run the phone to auto-shutoff, then charge to 100% without interruption to reset the baseline.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display draws a current spike the cell cannot sustain at that state of charge — voltage drops below the BMS cutoff threshold even though the gauge still shows charge remaining. It is a calibration issue, not a faulty cell. The fuel gauge IC is cutting power based on a voltage cliff it was not expecting at that percentage. Complete two full discharge-charge cycles and verify the phone shuts down only near 3.0V under load.