Franklin Wireless MHS800L Replacement Battery 3.8V 2100mAh

Franklin Wireless MHS800L — 3.8V Li-ion Replacement Battery

This is a 3.8V 2100mAh Li-ion battery for the Franklin Wireless MHS800L mobile hotspot. It slots into the MHS800L's battery bay and restores full charging capacity to the unit. The hotspot creates a portable 4G LTE WiFi network for travelers and remote workers who need connectivity away from fixed internet access.

• MHS800L fit: The MHS800L runs its cellular modem and WiFi radio off a single 3.8V Li-ion cell. This battery matches that voltage rail and the physical dimensions of the bay — 58.55 × 50.71 × 6.86mm — so the cover seats correctly and the contacts align.
• Bench tested on actual hardware: We ran this cell under combined cellular modem and WiFi load — four connected client devices, mid-range signal. The BMS held stable voltage through the draw cycle and tripped protection at the correct low-voltage threshold without cutting out prematurely.
• Ventilation during long sessions: Keep the MHS800L on a hard, flat surface during extended use — not in a pocket or bag. When connected devices are far from the hotspot, the cellular radio runs at maximum transmit power, and trapping that heat accelerates cell wear.

Hotspot disconnecting users mid-session on a new battery

The MHS800L draws from two simultaneous loads — the cellular modem and the WiFi radio. At maximum connected devices, that combined draw can pull voltage down faster than a degraded or low-capacity cell can recover. The BMS interprets the sag as a low-voltage event and cuts output to protect the cell, which drops all connected clients. A fresh 2100mAh cell with a healthy internal resistance handles these combined spikes without triggering the cutoff.

MHS800L won't power on after sitting unused

Li-ion cells self-discharge during storage — typically 1–2% per month at room temperature. If the MHS800L sat unused for several months, the battery may have dropped below the minimum boot voltage, which is around 3.0V on this cell chemistry. The BMS blocks charging from that state on some chargers to prevent an unsafe charge into a deeply depleted cell. Connect the hotspot to a wall adapter and leave it for 15–30 minutes before attempting to power on — a USB port may not supply enough current to recover the cell.