Sprint 803S 4G LTE Compatible Battery W-4 3.7V 2000mAh

Sprint 803S 4G LTE / SWAC803SMH — 3.7V Li-ion Replacement Battery (W-4)

This is a 3.7V Li-ion battery rated at 2000mAh (7.4Wh), built to fit the Sprint 803S 4G LTE mobile hotspot (also sold as the SWAC803SMH and Aircard 803S). It replaces OEM part numbers W-4 and 1202395 directly. If the original battery swells, no longer holds a charge, or won't boot the unit, this is the direct swap.

• 803S / SWAC803SMH / Aircard 803S fit: All three model designations refer to the same Sierra Wireless-made hotspot unit sold under the Sprint brand. They share the same battery bay dimensions (69.60 × 49.55 × 6.20mm), connector pinout, and BMS handshake — one battery covers all three.
• Bench tested on actual hardware: We ran this battery through full charge and discharge cycles on the 803S platform. The BMS communicated correctly with the hotspot's charge controller, accepted a full charge without flagging errors, and held voltage within expected range under simultaneous modem and Wi-Fi radio load.
• Ventilation during extended sessions: Keep the hotspot on a hard, flat surface — not a couch cushion or bag pocket. When connected devices are far away, the cellular radio pushes to maximum output power. That heat has nowhere to go if airflow is blocked, and sustained elevated temperature accelerates cell degradation over time.

Hotspot disconnecting users mid-session on a new battery

The 803S draws power from two radio subsystems simultaneously — the 4G LTE modem and the 2.4GHz Wi-Fi radio. At maximum connected clients, both radios run at full duty cycle. A battery with weak internal resistance can't sustain that combined current draw without a voltage sag. When cell voltage dips below the BMS cutoff threshold, the hotspot drops the connection or reboots entirely. A fresh cell with low internal resistance eliminates that sag — confirming it fixes the issue.

803S won't power on after sitting unused for weeks

Li-ion cells self-discharge at roughly 2–3% per month. If the 803S was stored partially charged or left in a hot location, the battery may have dropped below the minimum boot voltage — typically around 3.0V per cell. At that level, the BMS locks the output rail to protect the cell, and the hotspot shows no signs of life. Plug the unit into its charger for at least 15–20 minutes before attempting to power on; the charger's pre-charge circuit needs to bring the cell above the BMS re-enable threshold before the device will respond.