ZTE N9120 Li3817T42P3h735044 Compatible Battery 3.7V 3600mAh

ZTE N9120 / Avid 4G — 3.7V Li-ion Replacement Battery (Li3817T42P3h735044)

This is a 3.7V, 3600mAh Li-ion battery for the ZTE N9120 and Avid 4G smartphones. It matches the OEM part number Li3817T42P3h735044 and fits the same battery bay without modification. Voltage and physical dimensions — 73.15 × 49.60 × 8.90mm — match the original cell specification.

• N9120 and Avid 4G platform fit: Both devices share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. One cell covers both models because ZTE used the same hardware platform across the N9120 and its Avid 4G variant.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the N9120 platform. The BMS handshake completed correctly, charge IC accepted the cell without interruption, and no thermal flags were triggered during the full charge cycle.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This allows the fuel gauge IC to recalibrate its discharge curve against the new cell before high-current charging begins on an uncalibrated coulomb counter.

Why the N9120 reports wrong battery percentage after a cell swap

The N9120 uses a fuel gauge IC that stores a charge curve based on the old cell's internal resistance and discharge profile. When a new cell goes in, the IC is still reading against that old curve. This causes the percentage display to jump, stall, or read higher than the actual state of charge. One full discharge to auto-shutoff followed by an uninterrupted charge to 100% forces the IC to rewrite its reference curve to the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below what the modem or display load requires, even though the fuel gauge still shows charge remaining. On the N9120, simultaneous LTE activity and screen-on load can pull enough current to cause a voltage sag below the BMS cutoff threshold — typically around 3.0V per cell — before the percentage reaches zero. It is more common in the first few cycles before the fuel gauge IC has recalibrated. Running one full discharge cycle resolves the mismatch between reported and actual capacity.