BLU G80 Replacement Battery C706342400P 3.85V 3800mAh

BLU G80 — 3.85V Li-Polymer Replacement Battery (C706342400P)

This is a 3800mAh, 3.85V Li-Polymer battery for the BLU G80 and G0290ww smartphones. It replaces OEM part C706342400P when the original cell has degraded, swells, or no longer holds a usable charge. Physical dimensions are 80.30 × 61.20 × 4.60mm — verify clearance before installation.

• G80 and G0290ww compatibility: Both models share the same PCB connector pinout, voltage rail, and BMS handshake protocol. One cell fits both variants without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a G80 unit. The BMS accepted the cell on first connection, thermal protection triggered correctly at load, and the coulomb counter tracked state-of-charge without fault codes.
• Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge-to-charge cycle at standard current. The fuel gauge IC maps its calibration curve against the new cell's discharge profile before fast charging pushes high current into an uncalibrated reference point.

Sudden shutdown at 20–30% on the BLU G80 after a cell swap

This happens because the fuel gauge IC still holds the discharge curve from the old, degraded cell. When the new cell hits a voltage point the old curve mapped as 20–30%, the IC signals low-battery shutdown even though actual capacity remains. The phone cuts power before the new cell is genuinely depleted. One full discharge-then-charge cycle forces the coulomb counter to rebuild its reference against the new cell and corrects the early-shutdown behaviour.

USB fast charge not activating on the first cycle after replacement

On first connection to a fast charger, the charge IC may default to standard 5V/1A input until it confirms the new cell's impedance is within protocol limits. This is a protective handshake, not a fault. Let the phone complete one full charge at standard rate. On the second cycle, the charge IC re-evaluates cell impedance and fast charging resumes — confirm by checking the charging indicator or pulling battery stats at 3.85V nominal.