Sierra Wireless AirCard 762s W-3 Replacement Battery 3.7V 2000mAh

Sierra Wireless AirCard 762s — 3.7V Li-ion Replacement Battery (W-3)

This 3.7V, 2000mAh Li-ion battery replaces the original W-3 cell in the Sierra Wireless AirCard 762s and 760s mobile hotspots. It also fits the Wi-Fi 4G FC80 and AirCard 760. Swap it when the original cell can no longer hold enough charge to keep your hotspot running through a work session.

• AirCard 760s and 762s platform: Both models share the same 3.7V nominal rail, W-3 connector footprint, and BMS handshake protocol. That means one cell works across the platform — no firmware difference between the two units changes how the battery communicates state-of-charge to the device.
• Bench tested on actual hardware: We ran this cell under combined modem and Wi-Fi load, cycling through charge and discharge. The BMS held the low-voltage cutoff correctly and passed state-of-charge data to the hotspot UI without error codes or false low-battery alerts.
• Ventilation during extended sessions: Keep the hotspot on a hard, flat surface when running it for several hours continuously. The cellular radio pushes to maximum transmit power whenever connected devices are at range limit — that sustained RF output generates heat that feeds back into the battery cavity.

Why the AirCard 762s drops connections mid-session on a new battery

The 762s runs two power-hungry subsystems simultaneously — the cellular modem and the Wi-Fi radio. When multiple devices connect and signal quality is marginal, both subsystems ramp to peak draw at the same time. This combined load can pull enough current to drag cell voltage below the BMS cutoff threshold momentarily, triggering a restart. It is not a faulty battery — it is a load spike the original aged cell also struggled with. Reduce connected device count or move closer to the cell tower to cut modem transmit power and stabilise voltage.

Hotspot shows solid power light but will not boot after sitting in a drawer

Li-ion cells self-discharge at roughly 2–3% per month in storage. A hotspot left unused for several months can arrive at a cell voltage below 3.0V — below the minimum the BMS allows for a boot sequence. The device may show no display response or cycle on and off immediately. Connect the hotspot to a charger and leave it for 30–45 minutes before attempting to power it on. Once the cell climbs back above approximately 3.2V, the BMS re-enables discharge and the unit will boot normally.