Franklin Wireless MHS900L Replacement Battery 3.8V 2100mAh

Franklin Wireless MHS900L — 3.8V Li-ion Replacement Battery

This 3.8V 2100mAh Li-ion battery replaces the factory cell in the Franklin Wireless MHS900L mobile hotspot. It fits the MHS900L directly and restores the device's ability to convert cellular signal to a shared Wi-Fi connection. Capacity is 2100mAh (7.98Wh) — use the product data figure, not third-party listings that vary.

• MHS900L platform fit: The MHS900L uses a 3.8V single-cell architecture with a specific connector orientation and BMS handshake. This battery matches that voltage rail and connector so the device boots and communicates charge state to the firmware correctly.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the MHS900L platform. The BMS reported charge state accurately across the range, and the device did not flag a battery error or enter safe mode at any point during testing.
• Ventilation during extended sessions: Keep the MHS900L on a hard, open surface when it is running multiple connected clients. The cellular radio pushes to maximum output when signal is weak, and heat trapped under fabric or inside a bag accelerates cell wear at 3.8V chemistry.

Hotspot disconnecting users mid-session on a new battery

A new battery dropping connections mid-session is almost always voltage sag, not a faulty cell. The MHS900L draws current from two subsystems simultaneously — the cellular modem and the Wi-Fi radio — and peak combined draw can pull the cell voltage below the BMS protection threshold momentarily. When that happens, the BMS cuts output to protect the cell and the hotspot drops all clients. Running fewer connected devices reduces peak draw. If the issue persists, check that the battery contacts are fully seated, as a loose connection amplifies voltage drop under load.

MHS900L won't power on after sitting unused for several weeks

Li-ion cells self-discharge during storage, and if the MHS900L sat unused long enough the cell may have dropped below the minimum boot voltage — typically around 3.0V for a 3.8V nominal cell. The device will not power on if the BMS has locked the cell out of the discharge path. Connect the hotspot to a charger and leave it for 20–30 minutes before attempting to power on. If the charge LED does not activate at all, try a different USB cable and power adapter before assuming the battery is at fault.