About this replacement
ZTE Nubia Z5 NX501 — 3.8V Li-Polymer Replacement Battery (Li3822T43p3h844941)
This is a 3.8V, 2300mAh Li-Polymer replacement battery for the ZTE Nubia Z5 and NX501 series smartphones. It fits the original battery slot and connector on the NX501 and NX401 platforms. Capacity is 8.74Wh, matching the OEM cell specification.
- NX501 and NX401 platform fit: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers the full Nubia Z5 line without modification.
- Bench tested on actual hardware: We cycled this cell through charge and full discharge on an NX501 board. The BMS accepted the cell on first connection, stepped through CC/CV charging correctly, and held cutoff at the expected low-voltage threshold without triggering protection lockout.
- Fuel gauge recalibration on first use: After installation, run one full discharge to 5–10% and charge to 100% without interruption before enabling fast charging. The Nubia Z5's fuel gauge IC maps its coulomb counter to the new cell's discharge curve on that first cycle — skipping it causes the OS to report inaccurate percentages from day one.
Sudden shutdown at 20–30% on the Nubia Z5 after a cell swap
This is a voltage cliff issue, not a capacity defect. When the modem or display pulls a high current burst, a freshly installed cell with an uncalibrated fuel gauge IC can drop below 3.4V instantaneously — enough for the BMS to cut power even though the displayed percentage looks fine. The phone shuts off because the protection circuit sees a genuine undervoltage event, not a software glitch. Running one full uninterrupted discharge-charge cycle lets the coulomb counter anchor to the new cell's actual voltage curve and eliminates these cutoffs.
Phone feels warm near the battery during the first few charges
A new Li-Polymer cell has higher internal impedance than a worn cell — the charge IC on the Nubia Z5 responds by pushing slightly more voltage to compensate, generating more heat at the cell surface than you'd see on a broken-in battery. This is normal for the first two to three charge cycles as the cell's impedance drops. If warmth continues past cycle three or the phone becomes hot to the touch, check that the charge IC is not stuck in a fast-charge mode — disable any turbo charging option in settings and verify the charger output does not exceed 5V/2A for the break-in period.