Sierra Wireless Overdrive 4G W-1 Compatible Battery 3.7V 1500mAh

Sierra Wireless Overdrive 4G / Aircard 753S — 3.7V Li-ion Replacement Battery (W-1 / BATW801)

This 3.7V 1500mAh Li-ion battery replaces the OEM pack in the Sierra Wireless Overdrive 4G, Overdrive 4G+, and Aircard 753S series mobile hotspots. It fits the original battery bay without modification and connects to the same BMS handshake points as the factory unit. Use the capacity figure here — 1500mAh — not third-party listings that vary widely.

• Overdrive 4G and Aircard 753S platform: These models share the same 3.7V single-cell architecture, connector pitch, and BMS communication protocol — which is why one battery covers the full lineup. Swapping between them does not require firmware changes or recalibration.
• Bench tested on actual hardware: We cycled this cell through the Overdrive 4G with six simultaneous client devices connected. The BMS held voltage above the 3.0V cutoff threshold throughout heavy combined modem and WiFi draw, with no false low-battery shutdowns triggered.
• Ventilation during extended hotspot sessions: Keep the hotspot on a hard, flat surface with the vents clear when running it continuously for hours. When client devices are at the edge of WiFi range, the radio boosts to maximum output power — that sustained draw heats the cell faster than normal browsing sessions.

Overdrive 4G dropping all connected clients mid-session on a new battery

A fresh Li-ion cell can still trigger the BMS protection circuit if the combined modem and WiFi radio load exceeds the cell's instantaneous discharge ceiling. On the Overdrive 4G, this happens most often when the hotspot is at maximum client connections and the cellular signal is weak — the modem ramps to full transmit power exactly when the WiFi stack is also at peak draw. The voltage sags below the BMS cutoff momentarily, and the unit shuts down even though the battery reads 60–70% on the indicator. Reducing active client count or moving the device closer to a cell tower eliminates most of these mid-session drops.

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

Li-ion cells self-discharge at roughly 2–3% per month, but if the battery was already partially depleted before storage, it can drop below the minimum boot voltage — typically 3.0V on this platform. At that level, the BMS blocks discharge to protect the cell, and the unit appears completely dead with no LED response. Connect the hotspot to a wall charger, not a USB port, and leave it for at least 20 minutes before attempting to power on — a 5V/1A wall adapter delivers enough current to wake the BMS recovery circuit. If the LED flashes once and stops, the cell has recovered enough to begin a normal charge cycle.