AT&T Velocity 2 Replacement Battery 3.85V 3000mAh Li-Polymer

AT&T Velocity 2 — 3.85V Li-Polymer Replacement Battery (Li3930T44P4h794659)

This 3.85V, 3000mAh Li-Polymer battery is a direct-fit replacement for the AT&T Velocity 2 mobile hotspot. It matches the OEM part number Li3930T44P4h794659 and fits the original battery bay without modification. Capacity is 3000mAh (11.55Wh), identical to the factory specification.

• Velocity 2 fitment: The Velocity 2 uses a slim Li-Polymer cell at 3.85V nominal to keep the chassis thin while feeding both the cellular modem and the 2.4/5GHz Wi-Fi radio simultaneously. This cell matches that voltage rail and the original connector orientation so the BMS handshake completes normally on first boot.
• Bench tested on actual hardware: We cycled this battery under combined modem-plus-Wi-Fi load to confirm the BMS did not trip on startup draw. Charge acceptance was clean from 0% to full, and the protection circuit responded correctly to over-current events.
• Session heat management: Keep the Velocity 2 on a hard, flat surface during extended hotspot sessions — fabric or soft surfaces block the rear vents. When connected devices are far from the hotspot, the cellular radio runs at maximum transmit power, which raises internal temperature and accelerates cell wear over time.

Velocity 2 dropping connections mid-session on a new battery

When the Velocity 2 reaches its maximum connected-device count and signal conditions are poor, the cellular modem and Wi-Fi radio draw peak current simultaneously. A degraded or deeply discharged cell cannot sustain that combined load — voltage sags briefly below the BMS cutoff threshold, causing the hotspot firmware to restart the radio stack. This looks like a Wi-Fi dropout to connected users but is actually a protection-circuit event at the battery level. Replacing the cell resolves this if the original battery has lost capacity; check battery status in the device web UI at 192.168.1.1.

Velocity 2 won't power on after sitting unused

Li-Polymer cells self-discharge at roughly 1–3% per month. If the Velocity 2 sits unused for several months, the battery can drop below the minimum boot voltage — typically around 3.0V per cell — and the BMS locks out discharge to prevent damage. The device will appear completely dead even when placed on charge. Connect the hotspot to a charger for at least 30 minutes before attempting to power it on; this allows the BMS to detect safe voltage and re-enable the discharge path. If the indicator light does not respond after 60 minutes on charge, the original cell has likely reached end-of-life.