Edimax 3G-6210n Replacement Battery 3.7V 1800mAh

Edimax 3G-6210n / 3G-1880B — 3.7V Li-ion Replacement Battery (445NP120 / SP-1880)

This is a 3.7V 1800mAh Li-ion battery for the Edimax 3G-6210n, 3G-1880B, and BR-6210N mobile hotspot routers. It slots directly into the battery bay and restores power to the onboard cellular modem and Wi-Fi radio. Capacity is 1800mAh (6.66Wh), matching the original specification.

• 3G-6210n, 3G-1880B, and BR-6210N compatibility: These three models share the same battery bay dimensions, 3.7V single-cell architecture, and connector pinout. The BMS in each unit reads the same charge profile, so no firmware or hardware modification is needed.
• Bench tested on actual hardware: We ran this cell under a simulated multi-device load — cellular modem active plus Wi-Fi radio at full output. The BMS held the charge curve without triggering an over-current cutoff, and the protection circuit responded correctly to a deliberate deep-drain test.
• Ventilation during extended hotspot sessions: Keep the device on a hard, flat surface — not a bag or pocket — during long sessions. When connected devices are far from the hotspot, the cellular radio ramps to maximum transmit power. That heat accumulates inside the casing and accelerates cell degradation over time.

Why the 3G-6210n drops Wi-Fi clients mid-session under load

When multiple clients are active simultaneously, the combined draw from the cellular modem and the Wi-Fi radio can spike the current demand beyond what an aged or undercharged cell can sustain. Voltage sags briefly below the BMS cutoff threshold, and the device resets to protect the cell. A new cell with full charge capacity handles those combined peaks without the sag. If drop-outs persist after fitting a fresh battery, check that the hotspot firmware is up to date — some early builds have an aggressive low-voltage cutoff set above 3.3V that triggers false resets.

Hotspot shows battery indicator but won't boot after sitting unused

After extended storage, the cell voltage can fall below the minimum boot threshold — typically around 3.0V for this platform — and the device won't start even though the indicator may flicker. The BMS enters a protection state and blocks normal charging until a slow pre-charge pulse raises the cell above that floor. Connect the hotspot to the charger and leave it undisturbed for at least 30 minutes before attempting to power on. If the charge LED doesn't activate within five minutes, the original cell has likely failed and replacement is the correct next step.