ZTE X760 Li-ion Replacement Battery 3.7V 650mAh

ZTE X760 / Vegas Series — 3.7V Li-ion Replacement Battery (Li3706T42P3h413457)

This is a 3.7V, 650mAh Li-ion cell for the ZTE X760 and its close variants — the X761, Vegas, and S618. It replaces part number Li3706T42P3h413457 when the original cell can no longer hold a usable charge. Physical dimensions are 40.60 × 34.00 × 5.60mm, so confirm clearance in the battery bay before installing.

• X760, X761, Vegas, S618 compatibility: These models share the same battery bay dimensions, connector pinout, and BMS communication protocol — one cell fits all. The fuel gauge IC handshake is consistent across the group, so the replacement cell registers correctly with the OS on each device.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the X760 platform. The BMS accepted charge current without tripping, the fuel gauge IC reported state-of-charge correctly after one full cycle, and the connector seated flush without forced fit.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes into an uncalibrated cell — preventing early percentage drift.

Why the X760 reports wrong battery percentage after a cell swap

The X760 uses a coulomb counter that builds its discharge model against the original cell over hundreds of cycles. When a new cell goes in, the stored model no longer matches the actual discharge curve of the replacement. The OS reads the old curve and reports inaccurate percentages — often showing 100% well before full charge, or dropping suddenly at mid-range. One full uninterrupted discharge-charge cycle without fast charging resets the counter to the new cell's curve.

Sudden shutdown at 20–30% remaining on the X760

This happens when the cell voltage drops below the modem's minimum rail voltage under load — typically around 3.4–3.5V — even though the fuel gauge still reports charge remaining. It is a voltage sag issue, not a capacity issue. The phone's modem and display draw peak current simultaneously, and a degraded or newly installed uncalibrated cell cannot sustain voltage through that spike. After the fuel gauge recalibration cycle described above, verify the phone does not shut off below 3.5V under load.