Garmin inReach SE Replacement Battery 3.8V 3100mAh

Garmin inReach SE / Explorer+ — 3.8V Li-Polymer Replacement Battery (361-00107-00)

This 3.8V, 3100mAh Li-Polymer cell replaces the original battery in the Garmin inReach SE, inReach SE+, and Explorer+ satellite communicators. These devices handle two-way satellite messaging, SOS signalling, and GPS tracking in areas with zero cellular coverage. Keeping this battery in good condition is the only thing standing between a user and full off-grid communication.

• inReach SE, SE+, and Explorer+ compatibility: All three models share the same battery bay dimensions, connector pinout, and BMS handshake protocol around the 361-00107-00 cell — a single cell fits across the platform without modification.
• Bench tested on actual hardware: We cycled this cell through satellite acquisition, active two-way messaging, and SOS standby modes. The BMS held charge cutoff at the expected 4.2V ceiling and triggered low-voltage protection cleanly at the 3.0V floor with no spurious shutdowns.
• Cold-start acquisition after fitting: After any full power interruption, the inReach SE loses its ephemeris data and performs a GPS cold start. Take the device outside with a clear sky view immediately after first power-on — expect the initial satellite fix to take 5–10 minutes. Subsequent warm starts drop that back under a minute.

Why the inReach SE cuts off before the battery indicator hits empty

The inReach SE reads remaining charge through a fuel gauge IC that calibrates itself over full charge-discharge cycles. When a new or long-stored cell goes in, that gauge is uncalibrated — it can show two or three bars remaining while the actual cell voltage is already at the BMS cutoff threshold. The device shuts off without warning because the hardware low-voltage trip fires before the display catches up. Running two full charge cycles from flat to full recalibrates the gauge and brings the indicator back in sync with real voltage.

Saved routes and waypoints gone after a battery swap

The inReach SE stores user waypoints and some route data in battery-backed volatile RAM. A complete power loss — which happens every time the cell is removed — clears that memory. Tracks and messages synced to the Garmin Explore app or MapShare portal before the swap are recoverable. Any waypoints or routes stored only on the device and not synced beforehand are gone. Before pulling the battery, open the Garmin Explore app and force a full sync — confirmed by a green tick on the sync status screen.