About this replacement
Moxee K779 Series — 3.7V Li-ion Replacement Battery (BP1672)
This is a 3.7V, 1840mAh Li-ion replacement battery for the Moxee K779 mobile hotspot. It fits the K779, K779HSDG_P, and K779HSDL variants. Swap it when the original cell can no longer hold enough charge to keep the hotspot running through a full session.
- K779 variant compatibility: The K779, K779HSDG_P, and K779HSDL all share the same battery bay dimensions, connector pinout, and BMS handshake protocol — the BP1672 cell fits and communicates correctly across all three.
- Bench tested on actual hardware: We ran this cell under combined modem and Wi-Fi load with six connected clients. The BMS held steady through the draw cycle, showing no spurious low-voltage cutoff events.
- Ventilation during extended sessions: Keep the K779 on a hard flat surface with the vents clear during long sessions. When connected devices are far away, the cellular radio pushes to maximum output power — that heat feeds directly into the battery cavity and accelerates cell wear.
Why the K779 drops all connected clients mid-session
The K779 runs two power-hungry subsystems simultaneously — the cellular modem and the Wi-Fi radio. At maximum client count, the combined draw can spike voltage below the BMS cutoff threshold, triggering a protective shutdown. A degraded cell has less headroom to absorb these spikes. A fresh 1840mAh cell restores that buffer, so the BMS does not trip during normal multi-device loads.
K779 showing solid power LED but refusing to boot
When a Li-ion cell discharges below roughly 3.0V during storage, the BMS locks out normal boot to protect the cell. The hotspot may show an LED response but the system will not initialise. Connect the K779 to its original charger for at least 15–20 minutes before attempting a power-on — this brings the cell above the BMS re-enable threshold. If the device still will not boot after that charge window, measure terminal voltage at the battery; anything below 3.2V confirms the old cell needs replacement.