Globalsat BT-359 GPS Replacement Battery 3.7V 1100mAh

Globalsat BT-359 / TR-101 Series — 3.7V Li-ion Replacement Battery (LIN-331)

This 3.7V, 1100mAh Li-ion cell replaces the original battery in the Globalsat BT-359, BT-359W, TR-101, and TR-102 portable GPS receivers. It matches the OEM voltage rail and physical footprint at 52.90 × 38.12 × 8.02mm. Capacity is 4.07Wh, identical to the factory specification.

• BT-359 and TR-101/102 platform compatibility: These four models share the same battery bay dimensions, 3.7V single-cell architecture, and connector orientation — one cell covers all four without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on GPS hardware and confirmed the BMS holds the 4.2V charge ceiling and cuts off cleanly at the low-voltage threshold without triggering a hard fault.
• Cold-start behaviour after fitting: After fitting this cell, power the unit on outdoors with a clear sky view. The GPS performs a full cold start after any complete power removal — first satellite acquisition takes 5–10 minutes. Subsequent warm starts drop to under a minute once ephemeris data is cached.

GPS accuracy reducing at low battery on the BT-359

When battery voltage drops below roughly 3.5V, some GPS receivers throttle receiver sensitivity to reduce current draw and extend operating time. On the BT-359, this shows up as position drift or wider accuracy circles on the display. The fix is straightforward — the effect reverses once the unit is running on a freshly charged cell. If accuracy problems appear mid-session, check the battery indicator and recharge before your next use.

Device shuts off without warning before the low-battery indicator appears

This happens when the fuel gauge or voltage threshold indicator is uncalibrated against the new cell. The BMS protection circuit cuts power at its hard floor — typically 3.0V — before the device's own software indicator has had a chance to display a warning. Run two full charge-to-cutoff cycles to let the device recalibrate its voltage curve. After those cycles, low-battery warnings should appear at the correct point before shutdown.