ZTE MF90 Replacement Battery 3.7V 2000mAh Li-ion

ZTE MF90 / MF91 Series — 3.7V Li-ion Replacement Battery (Li3723T42P3h704572)

This is a 3.7V, 2000mAh Li-ion replacement battery for the ZTE MF90 mobile hotspot and its variants, including the MF91, MF91D, and MF90C. It matches the original OEM part number Li3723T42P3h704572 and the alternate Li3720T42P3h704572. It restores power to hotspots where the original cell has degraded or failed entirely.

• MF90 / MF91 family fit: These models share the same battery bay dimensions (72.00 x 45.10 x 7.30mm), connector pinout, and BMS communication protocol, so one cell covers the full range without modification.
• Bench tested on actual hardware: We ran this battery under simultaneous Wi-Fi client load and active cellular data transfer. The BMS held the discharge curve without triggering undervoltage cutoff during combined modem and radio draw.
• Signal-strength heat management: Keep the hotspot near a window or with clear airspace around it. When the cellular signal is weak, the modem pushes to maximum transmit power — that sustained RF output generates heat directly beside the battery cell and accelerates capacity fade over time.

Why the MF90 drops Wi-Fi clients mid-session under full device load

The MF90 runs two power-hungry subsystems at once — the cellular modem and the Wi-Fi radio. When all available client slots are active and the modem is pushing data, current draw spikes sharply. A worn or partially discharged cell can't sustain that combined load without a voltage dip. The BMS interprets a dip below its protection threshold as an unsafe discharge event and cuts output, disconnecting every client on the hotspot simultaneously.

Hotspot shows charging but won't boot after sitting unused for weeks

Li-ion cells that self-discharge below approximately 2.5V trip the BMS into deep-discharge lockout. The device will draw charge current and show an indicator light, but the BMS won't release power to the board until the cell recovers to a safe voltage — typically around 3.0V. Leave the hotspot on charge undisturbed for 30 to 60 minutes before attempting a power-on. If the cell recovers past 3.0V and the device still won't boot, reseat the battery to rule out a contact issue.