Neffos C7 Dual SIM Compatible Battery NBL-35B3000 3.85V 2900mAh

Neffos C7 Dual SIM — 3.85V Li-Polymer Replacement Battery (NBL-35B3000)

This is a 3.85V, 2900mAh (11.17Wh) Li-Polymer battery built to replace the original NBL-35B3000 cell in the Neffos C7 Dual SIM. It fits the C7 Dual SIM, C7 Dual SIM LTE AM, TP910C, and TP910A. Same connector, same physical footprint at 81.00 x 63.70 x 3.60mm.

• TP910C and TP910A compatibility: Both variants share the same battery bay dimensions, voltage rail, and BMS connector pinout as the standard C7 Dual SIM — one cell fits all four models without modification.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a TP910A unit. The BMS accepted charge from both standard 5V input and the device's native charge IC without triggering overcurrent protection or rejecting the handshake.
• Fuel gauge recalibration on first use: On first installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the C7 Dual SIM after a cell swap

The C7 Dual SIM's fuel gauge IC retains the discharge curve of the old cell in memory. When a new cell is installed, the IC misreads the voltage-to-capacity relationship and triggers a low-battery shutdown before the cell is actually depleted. This is a voltage cliff effect — the new cell's impedance profile differs from the worn original, so the gauge cuts power early. Fix it by running two full discharge-charge cycles at standard rate with fast charging disabled. After both cycles, the coulomb counter recalibrates and reported percentage aligns with actual cell state.

Phone shows wrong battery percentage after installing NBL-35B3000

The fuel gauge IC on the TP910A and TP910C was calibrated to the degraded curve of the original cell — not the fresh 2900mAh capacity of the replacement. Immediately after a swap, you may see the percentage jump erratically or plateau at figures that don't match actual charge state. Drain the battery fully until the phone shuts off on its own, then charge uninterrupted to 100% with the screen off. One full cycle is usually enough to reset the coulomb counter to the new cell's baseline.