Netgear Around Town 4G LTE Replacement Battery 3.7V 2200mAh

Netgear Around Town 4G LTE AC778AT-100NAS — 3.7V Li-ion Replacement Battery

This 3.7V 2200mAh Li-ion battery fits the Netgear Around Town 4G LTE mobile hotspot, including the AC778AT-100NAS. It replaces the original cell when capacity has degraded or the battery no longer holds a charge. Capacity figure is taken directly from product specification — 8.14Wh total energy.

• AC778AT-100NAS compatibility: The Around Town platform runs a single-cell 3.7V Li-ion configuration. The modem radio and Wi-Fi radio share one power rail, so the BMS must handle combined draw spikes when the hotspot is broadcasting to multiple connected devices simultaneously. This cell matches that voltage rail and connector footprint.
• Bench tested on actual hardware: We ran this cell under combined LTE modem and Wi-Fi load across multiple connected clients. The BMS held voltage without tripping under sustained draw, and the charge cycle completed cleanly from 0% to full without interruption.
• Signal environment tip: In areas with weak 4G signal, the cellular radio ramps to maximum transmit power continuously. Place the hotspot near a window or exterior wall — reducing the modem's output effort directly reduces heat buildup on the battery during long sessions.

Hotspot warm during extended sessions — what that means for the battery

The AC778AT-100NAS generates heat from two sources at once: the LTE modem and the Wi-Fi radio. When both run at full output — poor signal area, maximum connected clients — heat accumulates inside the enclosure. Li-ion cells degrade faster above 40°C, and repeated thermal cycles shorten usable capacity over time. Keeping the device elevated off flat surfaces and away from direct sunlight lets heat dissipate between the enclosure vents.

Hotspot not powering on after sitting unused for weeks

Li-ion cells self-discharge at roughly 2–3% per month at room temperature, but the AC778AT-100NAS draws a small standby current even when off, accelerating drain during storage. If the cell drops below approximately 2.5V, the BMS enters a protection lockout and the unit will not boot. Connect the hotspot to the original charger and leave it for 30–60 minutes before attempting to power on — this allows the charger to trickle current past the lockout threshold. If the LED shows no activity after that window, repeat the charge cycle from a wall outlet rather than a USB port.