ZTE MU500 Li-Polymer Replacement Battery 3.85V 4000mAh

ZTE MU500 / MU5001 5G — 3.85V Li-Polymer Replacement Battery (Li3945T44P4h815174)

This 3.85V, 4000mAh Li-Polymer battery replaces the original cell in the ZTE MU500, MU501, and MU5001 5G mobile hotspot devices. It matches the OEM part number Li3945T44P4h815174 and slots into the same housing without modification. Capacity is 4000mAh (15.4Wh), drawn from the product data.

• MU500 / MU501 / MU5001 5G compatibility: These three models share the same battery bay dimensions (80.80 × 50.26 × 7.50mm), the same 3.85V nominal rail, and the same BMS communication protocol — so one cell covers all three without any firmware or connector conflict.
• Bench tested on actual hardware: We cycled this cell under combined cellular-modem and Wi-Fi load across multiple connected clients. The BMS held the protection threshold correctly and did not trigger an undervoltage cutoff during simulated peak-draw sessions.
• Ventilation during extended sessions: Keep the MU500 on an open surface when it is acting as the sole hotspot for several devices. The cellular radio runs at maximum transmit power when clients are at range, and trapping that heat against the battery shortens cycle life faster than the draw itself does.

Why the MU5001 5G drains significantly faster than the MU500 on the same battery

The MU5001 5G modem draws roughly 30–50% more power than the 4G modem in the MU500 because 5G sub-6GHz radios maintain wider channel bandwidths and higher output power states continuously. This shows up as noticeably shorter use time even though both devices carry the same 4000mAh cell. Switching the MU5001 to 4G-only mode in the network settings reduces the radio draw substantially. If the device defaults back to 5G after a reboot, lock the network mode manually in the admin interface at 192.168.0.1.

MU500 not powering on after sitting unused for weeks

Li-Polymer cells self-discharge at roughly 2–3% per month, but the MU500's standby quiescent draw accelerates that — a stored device with the battery installed can drop below the minimum boot voltage (approximately 3.0V per cell) in a few months. When the BMS sees voltage below that threshold, it blocks output to protect the cell, and the device shows no response to the power button. Connect the hotspot to a 5V USB-C charger and leave it for 15–20 minutes before attempting to power on — this allows the BMS to detect charge current and exit the over-discharge lockout state. If the LED does not respond after 30 minutes on charge, the original battery has reached end of life and replacement is the next step.