About this replacement
ZTE U879 / Blade L2 / V879 — 3.8V Li-Polymer Replacement Battery (Li3820T43P3H636338)
This is a 3.8V, 2000mAh Li-Polymer cell that replaces the original battery in the ZTE U879, Blade L2, V879, and A75 smartphones. It matches the OEM part numbers Li3820T43P3H636338 and Li3820T43PH636338. At 63.00 × 62.22 × 3.57mm, it fits the original housing without modification.
- U879 / Blade L2 platform fit: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One cell covers all four variants without adapter or modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a ZTE U879 unit. The BMS accepted the cell without error flags, and the charge IC stepped through trickle, constant-current, and constant-voltage phases correctly.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.
Sudden shutdown at 20–30% on the replacement cell
The ZTE U879 uses a coulomb counter that was calibrated against the original cell's discharge curve. When a new cell goes in, the fuel gauge IC still references the old curve, so it misjudges the actual voltage cliff. Under modem or screen load, the cell voltage drops faster than the gauge predicts, and the phone cuts out before the percentage reaches zero. One full discharge-charge cycle — taken all the way down to automatic shutdown — resets the calibration window. After that cycle, the percentage readout tracks correctly under load.
Phone warm near the battery during the first charge after replacement
A fresh Li-Polymer cell has higher internal impedance than a cell that has been through several cycles. The charge IC pushes current into that higher impedance, and some of that energy dissipates as heat. This is normal for the first one to three charge cycles and settles as impedance drops with use. If the phone remains noticeably warm beyond the third full charge, check that the battery connector is seated flat — a partially lifted connector increases contact resistance and keeps impedance elevated.