ZTE U790 Hotspot Replacement Battery Li3717T42P3h654458 3.7V

ZTE U790 / MF63 / EUFI890 — 3.7V Li-ion Replacement Battery (Li3717T42P3h654458)

This 3.7V 1750mAh (6.48Wh) Li-ion battery replaces the original cell in the ZTE U790, MF63, and EUFI890 portable WiFi hotspot devices. It uses OEM part number Li3717T42P3h654458 and fits the same connector and cavity as the factory unit. Capacity is rated at 1750mAh — matching the original specification for these models.

• U790, MF63, and EUFI890 compatibility: These three models share the same 3.7V cell form factor, connector pinout, and BMS handshake protocol — that is why one replacement covers all three. Swapping between models on the same voltage rail does not require firmware changes or calibration steps.
• Bench tested on actual hardware: We cycled this cell under simultaneous modem and WiFi radio load — the BMS held the discharge curve within spec and triggered low-voltage cutoff cleanly without false shutdowns or thermal events at ambient temperature.
• Ventilation during extended hotspot sessions: When connected devices are far from the hotspot, the cellular radio runs at full output power to maintain signal. Place the U790 on a hard flat surface with nothing covering it — trapping heat against the battery during a long session accelerates capacity fade faster than cycle count alone.

Hotspot disconnecting users mid-session under maximum connection load

When several devices connect simultaneously, the U790 runs both the cellular modem and the WiFi radio at full draw at the same time. This combined current pull causes a voltage sag at the cell — if the battery is aged or partially discharged, the sag dips below the BMS cutoff threshold momentarily and the hotspot resets. A fresh cell with a full charge holds the voltage rail stable under that combined load. If drop-outs persist with a new battery, check whether the unit is also overheating, as thermal throttling can trigger the same reset behaviour.

U790 shows no boot screen after sitting unused for several weeks

Li-ion cells self-discharge during storage — the U790's BMS requires a minimum voltage at the cell terminals to initialise the boot sequence. If the battery has dropped below roughly 3.0V, the device will not respond to the power button at all, which looks identical to a dead unit. Connect the hotspot to a charger for at least 15 minutes before attempting to power on — this brings the cell above the BMS boot threshold. If the device still does not respond after 30 minutes on charge, the original cell has likely dropped below recovery voltage and replacement is the correct next step.