Garmin Montana 600 Replacement Battery 3.7V 1800mAh

Garmin Montana 600 Series — 3.7V Li-ion Replacement Battery (361-00053-00)

This 3.7V, 1800mAh Li-ion cell replaces the original rechargeable battery in the Garmin Montana 600, 600T, 650, and 650T handheld GPS navigators. It matches the OEM voltage rail, connector, and form factor. Fits the full Montana series that uses part number 361-00053-00 or 010-11599-00.

• Montana 600 and 650 series compatibility: These models share an identical battery bay, connector pinout, and BMS communication protocol. The same cell covers both touchscreen and non-touchscreen variants across the Montana line without modification.
• Bench tested on actual hardware: We ran this cell in a Montana 650T and confirmed the BMS accepted the charge cycle without flagging a fault. The device reported battery status correctly through the full charge and discharge curve.
• Cold-start behaviour after fitting: After fitting this cell, power the unit on outdoors and let it acquire a satellite fix before your first trip. A full power interruption triggers a cold start — expect the first fix to take 5–10 minutes. Subsequent warm starts drop back under a minute once the almanac is rebuilt.

Saved routes and waypoints disappearing after a battery swap

The Montana stores most user data — waypoints, tracks, and routes — in non-volatile flash memory, so a battery swap alone will not erase it. However, if the battery was fully depleted before removal, the unit may have lost unsaved active tracks held in battery-backed RAM. Always let an active track finish recording and save it manually before pulling the battery. After refitting, navigate to the Track Manager and confirm your saved data is intact before heading into the field.

Montana shutting off without a low-battery warning

This happens when the on-screen battery gauge is reading against the old cell's discharge curve. A new cell has a slightly different voltage-versus-capacity profile, so the Montana's indicator can jump from showing two bars to cutting off entirely with no warning. The fix is to run one full charge-discharge cycle in the device. After that single cycle, the gauge recalibrates to the new cell's curve and the low-battery warning fires at the correct threshold — around 3.5V — giving you enough lead time to save your position.