About this replacement
Garmin GPSMAP 276Cx — 3.7V Li-ion Replacement Battery (010-12456-06)
This 3.7V 5200mAh Li-ion cell replaces the factory battery in the Garmin GPSMAP 276Cx handheld GPS navigator. The GPSMAP 276Cx is a marine and outdoor navigation unit used for boating, fishing, and wilderness routing. It matches the OEM voltage and capacity spec, and fits the original battery bay without modification.
- GPSMAP 276Cx fit: The 276Cx uses a dedicated Li-ion pack with a keyed connector and a BMS that monitors cell voltage before the unit will power on. This cell matches that connector pinout and voltage threshold, so the device completes its startup handshake without errors.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the 276Cx. The BMS accepted the cell without fault flags, the unit reached full GPS functionality, and cell voltage held within spec across the discharge curve.
- Cold-start satellite acquisition: After fitting this cell, power the unit on outdoors in open sky and let it run until it acquires a full satellite fix. The 276Cx performs a cold start after any complete power interruption — first fix can take 5–10 minutes while it rebuilds its almanac. Subsequent warm starts drop back under a minute.
GPS accuracy reduced when the 276Cx battery drops below 20%
The GPSMAP 276Cx receiver draws more current during active navigation with a full map redraw and track logging running simultaneously. At low cell voltage — typically below 3.5V under load — the unit can reduce GPS receiver sensitivity to protect the power rail. This shows up as position drift or a reduced satellite count in the signal bar. Keeping the cell above 3.6V under load maintains full receiver performance.
Saved routes and waypoints missing after battery swap
The GPSMAP 276Cx stores most map data and waypoints in non-volatile flash, but active route state and some recent track logs sit in battery-backed RAM. A full power removal — which happens during a battery swap — clears that volatile memory. Saved waypoints in flash survive the swap; any active route loaded into RAM does not. Before swapping the battery, export active routes to the unit's internal storage or a microSD card using the Trip & Waypoints menu.