NET10 Savvy 3.7V 1400mAh Compatible Battery Li-ion Replacement

NET10 Savvy / Z750C — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1400mAh Li-ion cell for the NET10 Savvy, Z750, and Z750C. It fits the original battery slot and reconnects to the same charge circuit. Swap it in when the original cell no longer holds a usable charge between uses.

• Savvy / Z750 / Z750C compatibility: These three models share the same battery bay dimensions (59.40 × 46.00 × 5.10mm), the same 3.7V charge rail, and the same connector pinout — the reason one cell covers all three variants.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Z750C platform. The BMS accepted the full charge cycle without tripping, and the protection circuit responded correctly to low-voltage cutoff at the expected threshold.
• Fuel gauge recalibration on first cycle: After installing this cell, disable any fast-charge mode and run one complete discharge-to-charge cycle. This lets the phone's fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.

Why the Savvy reports wrong battery percentage after a cell swap

The fuel gauge IC on the Z750 platform stores a discharge curve calibrated to the original cell. A new cell has slightly different internal resistance, so the IC misreads state-of-charge from the first charge. The percentage display can read 20% higher or lower than the true level. One full discharge-to-charge cycle — battery run down until the phone shuts off, then charged uninterrupted to 100% — forces the IC to rewrite its reference curve against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under load — screen backlight, transmit burst, or a background app spike — faster than the fuel gauge predicted. The protection circuit reads the voltage cliff as a low-voltage event and cuts power before the displayed percentage reaches zero. The root cause is the uncalibrated fuel gauge, not a faulty cell. Run that first full discharge cycle and the shutdowns stop once the IC has an accurate voltage-to-capacity map for the new cell.