Garmin GPSMAP 276 8.4V Replacement Battery 3400mAh

Garmin GPSMAP 276 / 296 / 396 Series — 8.4V Li-ion Replacement Battery (010-10517-00)

This 8.4V, 3400mAh Li-ion cell replaces the original battery in the Garmin GPSMAP 276, GPSMAP 276c, GPSMAP 296, GPSMAP 396, and related models. These are portable marine and aviation GPS navigators used for waypoint tracking, route planning, and active navigation. Swap this in when the original cell no longer holds a usable charge.

• GPSMAP 276 / 276c / 296 / 396 platform fit: These models share the same battery bay dimensions, 8.4V two-cell Li-ion voltage rail, and BMS communication protocol — one cell covers the full group. The OEM part numbers 010-10517-00, 011-00955-00, and 010-10517-01 all map to this same physical format.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the GPSMAP platform. The BMS balanced correctly, the protection circuit tripped at the expected low-voltage floor, and the unit reported battery level accurately across the discharge curve.
• Cold-start satellite acquisition after swap: After fitting this cell, power the unit outdoors with a clear sky view and leave it running. The GPS performs a cold start after any full power interruption — first satellite fix typically takes 5 to 10 minutes. Subsequent warm starts drop that well under a minute once almanac data is cached.

GPS accuracy reduced at low battery on the GPSMAP 276 series

When cell voltage drops below roughly 7.0V under load, the GPSMAP 276 series reduces power to the GPS receiver to extend operating time. That reduction in receiver sensitivity lowers the signal-to-noise ratio on weaker satellite signals. In practice, position accuracy degrades and track logs show more scatter. Keeping the battery above the halfway charge mark during active navigation prevents the unit from entering this low-power receive mode.

GPSMAP shuts off without warning before the battery indicator hits empty

This happens when a degraded original cell can no longer hold voltage under the load spike of the GPS receiver and backlit display running together. The battery indicator reads a resting voltage that looks acceptable, but under draw the cell sags past the BMS cutoff threshold instantly. A fresh cell with full capacity eliminates this — the sag under load stays within the operating window. After fitting the replacement, do one full charge to 8.4V before extended use to let the fuel gauge recalibrate.