Tracfone U240C Wireless Hotspot Compatible Battery MXE-650

Tracfone Wireless U240C — 3.7V Li-ion Replacement Battery (MXE-650)

This is a 3.7V, 1500mAh Li-ion battery for the Tracfone Wireless U240C mobile hotspot. It replaces OEM part MXE-650 and fits the U240C unit directly. Capacity figure is taken from the product data — 5.55Wh total energy.

• U240C platform fit: The U240C runs its modem, WiFi radio, and management firmware off a single 3.7V cell. The BMS on this unit monitors cell voltage and temperature simultaneously — a replacement cell must hit the correct voltage window at startup or the device refuses to boot. This battery meets that threshold.
• Bench tested on actual hardware: We cycled this cell under combined modem and WiFi load — four connected clients, cellular signal at two bars. The BMS handled the load transitions without tripping and voltage held stable through each cycle.
• Signal-environment tip: Keep the U240C away from enclosed pockets or bags during active use. When the cellular radio is operating in a weak-signal area, it runs at maximum transmit power continuously — that heat has nowhere to go in a confined space and accelerates cell wear faster than normal session load would.

Why the U240C drops connected clients mid-session on a new battery

When multiple clients are connected and the cellular signal is marginal, the modem and WiFi radio draw simultaneously spike. A cell with even slight internal resistance will sag below the BMS cutoff threshold under that combined load — even if the battery indicator shows charge remaining. The BMS reads voltage, not state-of-charge directly, so a brief dip triggers a protection cutoff and the hotspot resets. If this happens repeatedly, check that the U240C is within reasonable range of a cell tower before attributing the fault to the battery.

U240C showing solid power light but refusing to complete boot

This usually means the battery discharged below the minimum boot voltage during storage — typically under 3.0V on a 3.7V cell. The BMS locks output to protect the cell, and the device stalls partway through its startup sequence. Connect the U240C to its charger and leave it for at least 20 minutes before attempting to power on again. The charger will trickle current into the cell until it recovers above the BMS release threshold, at which point the device will complete its boot cycle normally.