Verizon Jetpack AC791L Compatible Battery 3.8V 4300mAh

Verizon Jetpack AC791L — 3.8V Li-ion Replacement Battery (W-9)

This 3.8V, 4300mAh Li-ion battery fits the Verizon Jetpack AC791L mobile hotspot. It replaces OEM part numbers W-9, W-9B, and 308-10013-01. If your Jetpack shuts down unexpectedly or no longer holds a charge, this is a direct swap to restore full operation.

• AC791L fit: The AC791L runs a combined LTE modem and multi-device Wi-Fi radio from a single cell. The BMS on this battery matches the charge termination voltage and communication protocol the device expects — no error flags on startup.
• Bench tested on actual hardware: We cycled this battery through combined modem and Wi-Fi load on the AC791L. The BMS held stable at full multi-device draw and did not trip under the simultaneous radio output that typically stresses original cells.
• Ventilation during extended sessions: When connected devices are far from the hotspot, the cellular radio runs at maximum output power to maintain signal. Place the AC791L on a hard, open surface — not inside a bag or pocket — during long sessions to prevent heat buildup from accelerating cell wear.

Why the AC791L drops connections mid-session under full device load

The AC791L runs its LTE modem and 802.11ac radio simultaneously from a single 3.8V cell. At maximum connected devices, combined draw spikes sharply — especially when the modem is compensating for weak signal. A degraded or aging cell cannot sustain voltage at that draw, and the BMS triggers a protective cutoff before the battery physically depletes. The hotspot loses power briefly, drops all connected clients, and reboots. A fresh cell with full capacity handles the spike without voltage sag triggering the cutoff.

AC791L won't boot after sitting unused for weeks

Li-ion cells self-discharge during storage. If the AC791L sat unpowered long enough, the battery may have dropped below the minimum boot voltage — typically under 3.0V for a 3.8V nominal cell. At that level, the device's BMS locks out charging as a safety measure and the hotspot appears completely dead. Connect it to the OEM charger and leave it for 20–30 minutes without pressing the power button — most BMS circuits enter a trickle pre-charge mode that recovers the cell back above the 3.0V threshold before allowing a normal charge cycle to begin.