ZTE U790 Hotspot Replacement Battery 3.7V 1500mAh Li3717T42P3h654458

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

This is a 3.7V 1500mAh Li-ion replacement battery for the ZTE U790, MF63, and EUFI890 mobile hotspot devices. It matches the OEM part number Li3717T42P3h654458 and slots directly into the original battery compartment. Capacity figures come from the product data: 1500mAh / 5.55Wh.

• U790 / MF63 / EUFI890 platform fit: These three hotspot models share the same battery bay dimensions, connector pinout, and BMS communication protocol — that is why one cell covers all three. The voltage rail is identical at 3.7V nominal across the platform.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the U790 mainboard. The BMS handshake completed without error flags, and the protection circuit tripped correctly at the low-voltage cutoff threshold before cell voltage dropped below safe limits.
• Ventilation during active sessions: Keep the hotspot on a hard, open surface during extended use. When connected devices are at the edge of WiFi range, the cellular radio runs at peak transmit power — that heat transfers directly into the battery cavity and accelerates cell wear over time.

Mobile hotspot disconnecting users mid-session on a new battery

When the U790 is serving the maximum number of simultaneous clients, the combined draw from the modem and the WiFi radio can cause a brief voltage sag below the BMS trip threshold. The protection circuit reads that sag as an unsafe condition and cuts output — the hotspot reboots, dropping all connected users. This is not a defective cell; it is the BMS responding to a real current spike. Reducing the number of active connected devices or moving closer to a cell tower lowers radio transmit power and keeps the voltage rail stable.

Hotspot shows solid power LED but will not boot after sitting unused for weeks

Li-ion cells self-discharge at roughly 1–3% per month, but the U790 modem draws a small standby current even when switched off — together these can push the cell below the minimum boot voltage the BMS requires to release power to the mainboard. The device appears dead because the BMS has locked output to protect the cell from deep discharge damage. Connect the original charger and leave it for 20–30 minutes before attempting to power on; the BMS recovery circuit needs a trickle charge to bring cell voltage back above approximately 3.0V before it will unlock output.