NavGear GT-35 3D GPS Navigator Replacement Battery 3.7V 700mAh

NavGear GT-35 3D Series — 3.7V Li-Polymer Replacement Battery (WTL303580)

This 3.7V, 700mAh lithium-polymer cell replaces the original battery in the NavGear GT-35 3D, GT-35-128MB, GT35, and Pearl portable GPS navigators. It fits the slim internal bay and uses the same connector and voltage rail as the factory unit. Capacity figures are taken directly from product data at 700mAh (2.59Wh).

• GT-35 series compatibility: The GT-35 3D, GT-35-128MB, GT35, and Pearl variants share the same PCB voltage rail at 3.7V nominal and the same physical battery bay at 48.80 × 29.80 × 5.20mm. One cell covers all of them.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a GT-35 platform. The BMS accepted the cell without fault codes, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• First-use GPS cold start tip: After fitting this cell, power the unit on outdoors and let it acquire a full satellite fix before driving. GPS navigators perform a cold start after any complete power interruption — first fix takes 5–10 minutes compared to under a minute on subsequent warm starts.

GPS accuracy dropping at low battery on the GT-35

When cell voltage drops toward the lower end of the 3.7V nominal range, the GT-35's power management reduces current to the GPS receiver module. Lower receiver current means reduced signal sensitivity, which causes position jumps or a wider accuracy radius on-screen. This is not a software fault — it is the unit protecting itself from a hard shutdown mid-navigation. Keeping the cell charged above 3.6V measured at the terminals maintains full receiver sensitivity.

GT-35 shutting off without warning before the battery indicator hits empty

The on-screen battery gauge on the GT-35 is calibrated to the original cell's discharge curve. A new cell with a slightly different internal resistance will hit the hardware low-voltage cutoff threshold before the visual indicator counts down to zero. The unit cuts power abruptly rather than showing a low-battery warning. Run two full charge-discharge cycles and the gauge recalibrates — after that the warning and the actual cutoff align.