About this replacement
ZTE N988Z — 3.8V Li-Polymer Replacement Battery (N988Z)
This is a 3.8V, 3000mAh lithium-polymer battery for the ZTE N988Z smartphone. It slots into the original battery bay and connects to the same flex cable the factory cell uses. Capacity is 3000mAh (11.4Wh) — identical to the OEM specification.
- N988Z platform fit: The N988Z uses a fixed-connector Li-Polymer cell with a 3.8V nominal rail. The BMS on this device monitors cell impedance and temperature before allowing charge current. A cell that matches the original voltage and physical footprint — 75.00 × 56.16 × 6.10 mm — clears that handshake without triggering a charge fault.
- Bench tested on actual hardware: We cycled this cell through charge, idle, and load draws typical of LTE modem and screen-on use. The BMS accepted charge current on the first cycle, and no thermal cutoff events occurred during discharge to 3.2V.
- Fuel gauge recalibration on first use: On first installation, disable fast charging and run one full discharge-to-charge cycle at standard current. The N988Z's fuel gauge IC is calibrated against the old cell's discharge curve. One full cycle at normal current lets the coulomb counter re-map against the new cell before fast-charge currents are applied.
Why the N988Z reports wrong battery percentage after a cell swap
The N988Z uses a coulomb counter that learns the charge curve of whichever cell is installed. When you swap in a new cell, the counter still holds the old cell's data. The percentage readout can show 80% while the actual state of charge is significantly lower. One complete discharge down to the device's auto-shutoff point, followed by a full charge, flushes the old data and writes a new curve to the fuel gauge IC.
Sudden shutdown at 20–30% on the replacement cell
Li-Polymer cells have a voltage cliff near the bottom of their discharge curve — around 3.4V under load. The N988Z's modem and display pull current spikes that the fuel gauge does not fully anticipate when the cell curve is uncalibrated. The phone reads 25% remaining but the cell voltage drops below the BMS cutoff threshold the moment load increases. After the first full recalibration cycle, the fuel gauge maps this voltage cliff correctly and shuts down closer to the true 0% mark.